10am – a whole day’s walk ahead, but no idea where to go – none. I start heading west on the Central Line but with the possibility of branching back east at Stratford Overground or at Mile End on the District Line. Where will I end up at sunset? The Estuary appeals but not Essex nor the train journey out there. I need a river to follow to make my mind up for me.

I find myself at 10.30 on the C2C – a spontaneous decision at Stratford – my departure point decided at the moment I boarded without a ticket to take me beyond the Oyster Card zone which ends at Upminster. I relax with the most difficult part of the day over. I’ll be walking east from Upminster towards the Thames Estuary somewhere. Off the map now for me.

Leaving the Station it’s hard not to admire the Wimpy Bar – I need to return some day for a Knickerbocker Glory to relive childhood birthday treats. 11am and Upminster is starting to move. I stop for provisions at Waitrose – pork pie reduced to 55p, water, Cornish pasty and muesli bar. That should set me up for the day.

Passing beneath the M25 is the real point of departure – breaking free of the gravitational field of London into lands beyond. The drivers in Essex seem to want to kill you – there is a noticeable upping of the aggression when you walk out of London and emerge in an Essex country road. So the half-a-mile I walk along St. Mary’s Lane is pure terror. I’ve never been so happy to see a footpath as the one that branched off around the edge of a cornfield from a bend in the road – who cared where it was headed. Today would be a case study in the pros and cons of walking outside the city without an OS map – Apple maps lack public footpaths and contours – they merely give you enough of a hint as to where you are and which way you’re headed.

The footpath led to a level crossing and then continued up a steep climb chest-high with weeds and thistles.  The going was tough over rock hard plough in the searing heat. I drank most of my water. The footpath dumped me near an intersection of busy A-Roads – 2 miles in and I was nearly done. I decided to follow the A127 for a few miles – cover some ground with my head down beside the throbbing traffic. It seemed like a good idea at the time.

Twice I failed to find my way off the road – tightrope walking the slip road curbstone and rabbit running the roundabouts just to find myself back on the A127 on the other side. 19 miles to Southend – should I submit to an asphalt yomp and collapse into an amusement arcade at night in the ‘End?

Past a van abandoned on the pavement – all doors wide open, interior stripped bare. Past Brentwood Valeting Centre with the high performance cars queued up for some spit and polish. I had to escape the road.

The B-Road into Laindon went on-and-on, featureless, giving nothing away. I’d been walking 4 hours and was close to despair – write it off as a failed venture and get the train home from Basildon.

I was saved by a bridleway – innocuously enough heading away off the road encased in hawthorn. Two young kids chased Pokemon on their phones. I rested on a tree trunk on the high side of Langdon Recreation Ground munching on sweaty pork products and found the will the push on. I wanted to reach water at some point today – a sunset over the estuary would be a bonus.

The paths wending through trees crossed the road and take me into Langdon Hills Country Park. I get a rush of memories – school trip to Swanage during the Falklands War, Scout Camp in Hampshire when Liverpool beat Roma on penalties to win the European Cup, the walk in Rendlesham Forest on New Year’s Eve, hill villages in Thailand (from the smell of hay). I was so happy wandering through Coombe Wood, Great Sutton Wood and Northlands Wood that I was mildly amused when it transpired I’d walked in a giant loop back to where I’d begun. At that point I would have gladly seen out the rest of the day walking in circles in the Langdon Hills.

I did though eventually find my way into a field of tall swaying wheat with a footpath carved across the centre which ran into a wood on the far side but then ended beside the A13 near Stanford-le-Hope. I could bare no more roads so stuck to the edge of the field hoping to find an exit.

At the bottom of the field the perfect babbling brook ran in a deep gulley under the cool shade of the trees. I scooped soothing cold water over my head and neck before jumping across and scrambling up the far bank and across the road into Stanford-le-Hope. I’d been out of water for a while in the hot sun and rehydrated at the first available corner shop – sculling a can of 7-Up by the bins outside like I’d just emerged from a trek across the Sahara.

There was a clear route open now across the marshes to the Estuary – 6pm and heading towards that sunset over the water.

That first view of the Thames lapping over the mud flats at Stanford Wharf was priceless. I drank it in thinking now I’d be able to walk eastwards along the river. A family were putting away a picnic they’d had on a single square of sand on the shore surrounded by heavy clumps of salt marsh grasses. The path to Pitsea headed back inland – the sight of a level crossing induced flashbacks to the dark origins of this quest so I turned away. Another path ran alongside a high concrete wall beside the marshland – reminiscent of a similar path back near Tilbury Power Station I’d walked along a few times in the past, so I carried on assuming it would likewise hug the outside wall of the container port on the riverside.

Ascending a tall set of metal steps at the end I found myself caught in a peculiar pen – on a concrete platform jutting out into the river – the railway line behind me, and ahead the boulders lining the river bank. Refusing to turn back after all I’d been through the only available option was to clamber on over the rocks.

It soon became clear that this wasn’t exactly a legitimate pathway and could land me straight in the river at the end. There was no apparent exit so I clambered through a clump of thick brambles to a high concrete wall and found a point where, with my arms above my head and a bit of leap, I could attempt to pull myself over the wall.

Puffed out and adrenalized I paused lying face down atop the wall, I couldn’t fall down the other side until I’d worked out the extent of the drop and what was down there. Once satisfied it was safe I allowed myself to fall down into the tall weeds. Blood was streaming down my arms where I’d scraped them pulling myself over the wall. I tried to work out where I was. A building site beside the entrance to London’s new container terminal London Gateway owned by the Dubai government corporation DP World.

I waited assuming that security would be on their way and looked forward to being escorted out, it would be the first time today that I’d be sure where I was going – if I was lucky I might even get a lift, somewhere along the way I’d twisted my ankle and with the adrenalin ebbing away it was starting to hurt.

But nobody came – in fact there didn’t seem to be a soul around. And so I wandered the deserted new roads of this unnerving preview of the future. This vast terrain of blank box distribution units – the enormous robot cranes that automatically unload shipping containers once the work of tens of thousands of people. Compare this empty wasteland of sleeping robots with those images of the old crowded London docks. It sends a chill down the spine.

I wandered for an hour around the empty logistics park and didn’t see a single human being. Eventually I ran out of road and found myself at a high locked gate. The barbed wire ran into the horizon in one direction. My only escape was to jump a stream and awkwardly and carefully limbo my way between the barbed wire into a farmer’s field ripping my shirt in the process as the final injury of the day.

I did get my sunset. It wasn’t looking over the Estuary though – it was sitting on a mound in the centre of a roundabout at the main entrance to London Gateway – near where I’d clambered over the wall. I sat there with a supper of Co-Op Sandwich and another can of fizzy drink. I was sunburnt, worn out, scratched arms and ripped shirt. It had been a good walk.