Richard Harrison tracks history
If you stand on platform 4 at Blackfriars Thameslink station and look over the river on your right back towards the city on the Temple side, you'll see an arched drain entering the river. If you go to Kenwood House in Hampstead Lane and explore the grounds, you'll find a number of small springs and ditches which eventually lead to the lake and then to the chain of ponds at Highgate. Above the Vale of Health in Hampstead, there are springs which fill the Hampstead Ponds (the quest for the source of which much concerned Mr Pickwick and his friends).
If you were to drop a message in a bottle at either Highgate or Hampstead, it would (with luck) eventually emerge into the arched culvert in the Thames at Blackfriars. For this is the famous river Fleet and, whilst it is a river no more, it is both an underground waterchannel and a fashioner of the landscape. Its course can be tracked above the surface and its continuing influence can be spotted. This article follows its course up from Blackfriars.
The fact that New Bridge Street and Farringdon road are set in a river valley is obvious as you look up them. Ludgate Hill and Fleet Street descend the banks; Holborn viaduct is clearly a bridge; Seacoal Lane recalls the days when barges used to deliver coal from Newcastle up the Fleet estuary. Turnmill Street on the right denotes former local industry. There are of course tributaries, probably just ditches in fields, but just look at Cowcross Street (which the cows going to Smithfield had to cross), Margery Street and whatever flows across from Great Ormond Street.
Just before the Guardian newspaper offices, the trail leaves the Farringdon Road and bears left up Warner Street and Ray Street but even there the banks can be seen. The river turns to the right and goes under the viaduct of Rosebery Avenue, a river bridge if ever there was one. Then it turns up Phoenix place behind the ITN building on the left and Mount Pleasant sorting office on the right. Mount Pleasant is clearly high ground rising from a river as indeed are the steep hills of the Lloyd Baker estate further on. Pakenham Street and Cubitt Street feel like a watercourse and, just past them, in the rather confusing streets south of King's Cross, the river is adopted by the tracks of the Circle and Metropolitan lines.
There is a definite curve round King's Cross with the lighthouse on the right and then we swing up Midland Road between the two great and contrasting Victorian railway termini. The huge red brick wall of St Pancras seems to acknowledge the river's next curve to the left and it then bears to the right under the lattice of viaducts. You soon approach St Pancras Old Church which is mysterious and ancient. Even now the scene hints at its original setting in a wooded fields by a stream. Both it and Gospel Oak further up the course are focal points in the pagan London geomancy popularized by Ian Sinclair and Peter Ackroyd.
The hamlet of St Pancras was forsaken for the expanding Kentish Town further upstream. The river leaves St Pancras Way to follow the present course of the Regent's Canal up to Kentish Town Road: here the canal actually feels like a meandering river. It couldn't climb up the hill to Camden High Street (where the canal now uses three sets of locks). Instead it went right up past what used to be called the Castle and is now, regrettably, named "The Verge" (which I suspect has nothing to do with being beside a river). It is shown on old prints as a riverside tavern edged with pleasure gardens.
The real mystery of the Fleet is precisely where in Kentish Town it splits into its two tributaries. Some say it happens in the Industrial Estate over from Kentish Town Station, others site the split at Hawley Road. Like so much in life, it all depends on which map you use.
Anyway, one branch goes up to Hampstead and meets its tributary ponds by way of what is now the Gospel Oak Estate passing the Royal Free in Fleet Road and the hamlet of South End; the other passes Angler's Lane a Kentish Town street presumably named after the activities which used to take place on the banks. It criss-crosses Highgate Road - the course and river valley are clear in Burghley Road and a metal tube containing it crosses the railway line into York Rise. York Rise is clearly a river valley and the course of the river makes its waythrough Brookfield to the more pleasant chain of Highgate Ponds. Eventually it gets to Kenwood - which is where we started with our message in a bottle.
Here, at the celebrated viewing point, you can stand back and gaze over the great bowl of London and its landmarks beneath you. You can map out the course of the river you have followed and maybe some lines of the area's most celebrated poet will have some added resonance:
"Then would the years fall of and Thames run slowly;
Out into marshy meadow-land flowed the Fleet:
And the walled-in City of London, smelly and holy,
Had a tinkling mass house in every cavernous street."
Sir John Betjeman, "Monody on the Death of Aldersgate Street Station"
Note: the best immediate sources for further research are: "The Lost Rivers of London" by Nicholas Barton, "Kentish Town Past" by John Richardson, "The Fields Beneath" by Gillian Tindall - and the London A-Z.