This post is nothing to do with aviation. I was as far away from flying as I could possibly get, being underground and all. But pilots are adventurers and this was an adventure and so I hope that you will find this as interesting as I did.

I have been researching the original rivers of London, specifically the Fleet, which is a part of the famous Victorian sewer system designed by Bazalgette in the 1860s and 70s. I found photographs on various websites: dark brick curved walls with a trickle of grey water pooling at the centre, all edges fuzzy in the low light. I wondered if there was a way to see them for myself and, on a whim, I sent a message to Thames Water asking if that might be possible.

You could have knocked me over with a feather when they said yes.

They were kind enough to allow me to join them for an afternoon out at the Abbey Mills Pumping Station in West Ham, an industry event that included a descent into the sewers at the Wick Lane Depot. “Wear comfortable clothes,” they told me. “We’ll provide protective clothing including a harness and oxygen masks.”

It was raining as the bus pulled up to the pumping station and I dashed in, not paying much attention to the outside of Station A which was covered with scaffolding. The Grade II listed building has apparently been in need of a tidy-up for a while but now with the London Olympics bringing crowds walking directly past, the Victorian brickwork is receiving some attention. I know very little about architecture and I was not particularly interested in structural details.

Those of us who had no connection to the industry huddled together, discussing what had brought us on this tour and what we were most looking forward to. Many others, I discovered, were there specifically for the tour of the pumping station and one woman had already decided she was most definitely not going down into the sewer at all. I began to pay more attention to my surroundings.

Jokes were made about how long the speaker, Ben Nithsdale, would bore us about the history of London’s sewers. I squirmed in my seat. I shouldn’t have sat in the front row where the speaker would see if I dozed.

He began by telling us about the sewers at Wick Lane, of serious interest to us because we would soon be traipsing along them. They are 3 metres in diameter, he told us, and the water flow limited for our visit, so that we would only have about a foot of water to wade through. That didn’t sound like very much.

The water would normally go up to his chin, he told us, and if it rained, the tunnels would fill. This is what causes the pollution in the Thames. And with that, he took us back to the old rivers of London and the evolution of the water supply. We started in the 13th century and by 1730 and the creation of the New River, I was scribbling frantically, wishing there was some way I could take a copy of his speech with me.

I wrote three pages of notes before he even touched on the Bazalgette sewers and the work which began at Wick. But all too soon, it was over and we were led on a tour of the pumping station, affectionately referred to as the “Cathedral of Sewage.”

Thames Water staff speak about the architecture (Neogothic Italianate, apparently) and brick work (simply gorgeous) with clear admiration and affection. A heated argument was in progress as to whether the carved plants on the far side of the building were strawberries (the leaves, we were told by one adamant gentleman, were all wrong) or some other plant and he admitted that they had only just positively identified the peonies carved near the main entrance. The detail in the building is amazing, especially when you consider that it was built as a pumping station in the middle of the marshes. Even the drain pipes were beautiful.

“When you go down into the sewer, look at where the two tunnels meet. They didn’t just cut away the bricks to make the join, they formed them for the junction. It’s the finest quality brickwork down there. Breathtaking.”

Our tour guide was that perfect combination of informative and amusing, interspersing architectural details with anecdotes about the works and brief asides about office politics. He told us that the sun rises in the south because the wind vane was reattached to the roof by a man dangling by his ankles, who was not too fussed about making sure the directional markers were set correctly.

With a smile, he pointed out where the Luftwaffe had bombed the coal storage of station during World War 2. “If we were still using the coal, it would have been a disaster. However, the station was completely electrified by then. So thank you, Mr Goering, for our car park.”

He led us into the main pumping station and my mouth fell open. It was brilliant, a perfect Steampunk Fantasy. Disney could not have done it better. Robotic looking devices, gleaming brass, moulded stone around the pillars and twisted iron rails along catwalks, all towered over by ornamental arches.

This is a working station which kicks in when it rains. I felt like I had walked onto a movie set. I missed half the descriptions. I was wandering between the machines in a daze, reading oversized dials and trying to make sense of the pure glamour of this place which was built to pump sewage, for gods sake.

And they let us touch things.

I think I must have three dozen photographs of the the electrical motors, affectionately known as Daleks. And the high ceiling, the roof lantern surrounded by arched windows, well… I don’t know enough about architecture to explain it but this should be on your life list of things to see.

When I signed up, I thought I would “put up with” the tours of the buildings in anticipation of going down to the sewers. I was wrong. They had to drag me out with promises of the archive.

And oh, the archive! I’ve never been so close to such ancient books. Detailed maps of London were spread on broad tables. The modern maps were explicit: streets were marked with the pipelines detailed underneath with their diameter and depth. As we stepped back in time, we saw the maps with the pipelines marked but without an overlaying roadmap and with no information as to how deep the pipes were laid. The version before that looked like something from a teenager’s science project: brightly coloured lines and very little hard information. The bookshelves were stuffed with large leather-bound books. A further display of photographs showed the sewer workers – we were told they are called flushers – over the past century. I could have spent a day in that tiny little room alone. I tried to dawdle.

“The bus is going to leave without you. You’ll miss the sewer tour.”

Oh yes, the sewer tour. The whole reason that I came here today! I ran.

We were taken to the Wick Lane depot where the Wastewater Operatives – the flushers – were waiting. They confirmed that the sewer had been prepared for us. “We reduced the water flow for you,” said one man with a smile. “But don’t worry. We left all the good stuff in there.”

Oh, thanks.

First, we had to don our protective gear: thick woollen socks, disposable latex gloves and a white jumpsuit which fit easily over my clothes. Our escort looked at my long hair with dismay. “Do you have a hair band? Anything to tie it up with? Well, put your hood up, that will have to do.”

Have to do? I was only expecting to get my feet wet, not dive in!

We were then fitted with a harness and handed thigh-high waders. The man looked at my feet. “Size 5? Hah! This is a Size 7 Fits All.” I pulled them on and tried to get them up to my hips, as directed by the three Thames Water workers who, to their credit, never burst out laughing once, even when I tugged too hard and tipped myself over. The boots were too long for me (I’m only 153cm / 5-foot tall!) and I could not get the bunched up rubber to come up to the top of my thighs. I gave up and waddled to pick up my gloves: huge red Mickey Mouse gloves which I still don’t understand the purpose of. Finally, a bright blue helmet was gently placed over my hooded head.

Then they took a photograph of the group of us in all our glory. You can stop laughing now.

“You need to pull those boots up.”

“I know.” I tried not to whine. “I tried to.” I tugged ineffectually at them again.

The third person to inform me of this gave up and knelt in front of me to help. “I’m really sorry about this,” he said as he grasped the boots at my mid-thighs, “but it has to be better than getting sewage in your boots.” He tugged, hard, just about lifting me off the ground.

“Best time I’ve had all week,” I countered, genuinely grateful that he was helping me out. He grinned and called over a chaperone.

We were given a set of instructions including basics such as don’t splash and don’t panic. “And when you are ready to climb out? Don’t look up. Remember the person above you is dripping wet having just vacated the sewer.” We laughed nervously. I discovered one of the flushers, Daniel, writes The Sewerman’s Log which was a primary resource for me when I first started writing fictional scenes taking place under the city.

Finally, it was time. We queued up to be attached to the shiny metal hook, a winch to catch us if we slipped off the thin metal ladder as we climbed down 10 metres into the barrel below.

I worried about how thin and slippery the rungs were as I stepped on. I was petrified that my feet – encased in huge rubber boots – would slip out from under me. I stepped down carefully and then looked up. My gut clenched. Don’t look up! I panicked, trying to remember why. One by one, I brought my hands down and then carefully inched the next foot down a rung.

At the bottom, a soothing voice told me to step down one more time. “There’s a rung under the water level, just step down onto that, then step back off the ladder and turn to your left.”

I nodded but my fingers clenched the ladder even tighter. Step down then turn left, I thought, but I had no idea which way was left. I realised I was panicking over nothing and took a deep breath.

I lowered my foot into the liquid until I felt the last rung. I twisted to the left. The man put a hand on my shoulder. “Stop! Step off the ladder first and then turn left.”

I stepped back into the liquid, the quick current snatching at my rubber heels. I was thigh high in green-grey water streaming past me at a fast rate. I’d done it! I stared at the darkness around me spotlit by the helmet lights of the flushers. I was in a real Bazalgette tunnel, wading through real sewage. The rubber of the thigh-high wading boots felt chilly against my calves and I realised that although it was warm in the tunnels, the water was cold. I felt like I had entered some other world, an underground labryninth. An evil dungeon full of hate and bile.

“Turn left, love,” said the man. I apologised and released my grip on the rungs.

He handed me a bright orange sack holding 10 minutes of oxygen and an oxygen mask. The grit crunched beneath my feet as I shuffled up to the others. The next person quickly descended the ladder.

We edged along the middle of the barrel in single file, feet sliding against the rough ground of silt and gravel below. The water came up over my knees. I stared at the water as if I could see the ground beneath, fighting off the fear that I was about to get tipped off my feet and dragged along the tunnel, my helmet swirling in an eddy behind me. I expected to step through sludge, not wade through fast-moving sewage. I felt off-balance and out of sorts.

We shuffled forward, the flushers alongside us making sure we were steady.

I wasn’t. I’m of a shape that naturally bobs to the surface and I was wearing rubber waders that were two sizes too big for me. The current dragged at my legs. Every step I took, I worried that I was going to slip backwards and over. The flushers were vigilant and I regularly felt a hand at my elbow. Piles of grit crunched beneath my feet. I peered at the muck unhappily.

A bright smile appeared at my side. “Everything OK?”

“Just fine.” My tone was defensive. Certainly I could walk a few feet along a sewer without making a fool of myself. Bazalgette’s sewers! The excitement filled me. I was finally here!

Knowing I couldn’t handle a notebook in the sewers, I planned to rely on memorisation tricks. I would focus on the different senses and recite keywords to help me to remember the scents and sounds of the tunnels, the feel of the underground breezes, the spotlit views. I wanted to be able to write about London below convincingly.

I took a deep breath and focused on the warm air around me. Musty, dank, sweet, cloying… too many words to try to remember the sharp scent of the air. Even as I sniffed, it shifted to something different. My foot slid against a slick brick. My arm flailed towards the brickwork, one small part of my mind remembering that it was exquisite and I needed to take a better look. A strong arm came around me before I was even aware that I was slipping. I gasped, the sewer bouquet forgotten.

“You’re all right,” the flusher said, holding me steady. Then he smiled reassuringly. “Are you all right?”

“Yes.” And then, aware that I had been precariously close to slipping into a fast moving sewage stream, I smiled back. “Thank you.”

I slithered my feet forward, feeling for the gravel and slippery rocks through the rubber boots and woolen socks. The flusher, also known as the kindest person in the entire universe, took my hand and the hand of the woman behind me, making soothing noises as he walked alongside us. I tried not to clutch, my eyes firmly on the running water coming well past my knees now.

The tunnel (sorry, barrel) widened out and I could see streams of grey daylight reflecting against the green-grey water ahead. My best friend led me to another flusher, passing my hand over as if it were a Scottish country dance. “Look after her,” he told him.

My new best friend looked at me. “You need to pull those boots up,” he said.

“I’ve tried!” I must have sounded almost tearful. He bent over, face precariously close to the running water, and tugged.

“Well, that will have to do,” he said with a sigh. “Wade very carefully across and grab the rope.”

I slithered forward again, trying desperately not to splash. The water lapped at the top of my waders but didn’t quite make it over the edge. Then another flusher splashed through, water streaming behind him. I held my breath and stood on my tiptoes, trying not to think about woolly socks infused with raw sewage.

We lined up along the rope, weak beams of light streaming through gaps in the ceiling. I could see a modern metal catwalk above us and wondered if that was for rescuing people who fainted into the muck. Then our cameras were passed out so that we could take photographs.

The water only came up to my knees here and the current was less swift. However, the additional light and security of the rope were cancelled out by my fear of dropping my camera. I gulped and began taking photographs. It was difficult to get clear images in the low light without blasting the area with flash. I have a number of murky green/grey photographs with soft edges, exactly the type of image I complained about seeing on the web.

The Chief Flusher offered to answer any questions we might have but I couldn’t think of a single one.

He told us about the mounds of fat that gather in tunnels. “A tree passed through the sewers without causing any blockage but the fat gathers. You can see it at the edges here. We end up with mountains of fat blocking the sewers and they trap all the other detritus passing through.” He scowled. “Fat and baby wipes. They’re the worst.”

He spoke with some regret about overflowing untreated sewage into the river a few winters ago. “It was that or flood people’s houses with raw sewage,” he said with a sigh. “These sewers just aren’t quite up to the job.”

Bazalgette, he tells us, was a visionary. The size of the tunnels and the usage of Portland cement have meant the his sewers have taken care of London’s sewage for over 150 years despite rising populations. But it is a combined system, mixing rain water and natural run off with the foul water from our drains and toilets, so after heavy rain fall when the flow rises even more, the system becomes overloaded and there is nowhere for the sewage to go.

The Thames Tunnel will be the solution to this problem: a thirty-two kilometre storage tunnel which will run underneath the Thames.

Daniel of the The Sewerman’s Log offered to take a photograph of me and I happily handed over my camera, knowing it was more secure in his hands than mine. It turns out that a mix of fear and excitement cause me to grin like a loon.

And then, sadly, it was time to leave. We were led out through a parallel barrel which was slightly higher. The flusher spread themselves along the way. As I reached the first one, he held my elbows loosely and told me to reach forward with my foot until I felt the step up. I found the slick edge of a brick that would have had me sprawling if I’d encountered it without warning. Each flusher took us past the next few steps where the sewage level was lower but the footing much more treacherous. I was encouraged again to ask questions but I was already reeling with information. I had to get it written down for processing before I could think of anything new! I made it to the ladder where they connected me to the winch and bade me be careful climbing up, especially now that my boots were slick with … well, it might be slippery.

I made it to the top without incident, the dreary rainclouds seeming vibrantly bright after the dark of the tunnel. I stomped around in the tray of disinfectant they’d put out for us and then walked across to the changing rooms, where I promptly tripped over my oversized boots and stumbled to the ground. Thank god for that, I said, so relieved that it hadn’t happened down below.

That was the end of the most marvelous day out I could possibly imagine. I know this was an extra-ordinarily long post but it was an extraordinary day. Thames Water were unbelievably awesome for letting me go on this tour and everyone I met was so friendly and informative and so visibly proud of the Victorian enterprise that they worked in. Never was there a sense of resenting the old technology or wishing to avoid the issues of working in listed buildings (in fact, there were some snide comments about how ugly the newer buildings at the station were compared to their Victorian counterparts). Everyone was enthusiastic about the pumping stations and the sewers and pleased to be able to share some of that history. I cannot speak highly enough of the Thames Water representatives I met on my tour.

I have a Certificate of Completion from Thames Water Utilities which certifies that I have entered a J.W. Bazalgette sewer. I never thought I’d be so proud of being in deep shit.