The Pent Stream is an ancient watercourse flowing from the North Downs into the sea at Folkestone.  Large enough to be termed “river”, it is now hidden by urbanisation and only occasionally makes it presence felt.  In August 1996, a one in six hundred year event caused major flooding in Blackbull Road and down the Foord Valley, where you are now standing.  You can see evidence of the widespread devastation on the wall of the bar inside the Red Cow Pub opposite.

To appreciate and understand the course of the hidden Pent Stream it is essential to consider the basic geology of the area.  The southeast of England was formed by layers of Cretaceous sedimentary rock which were folded into an arch.  Water action removed the top of the arch and the bands of rock that were exposed eroded at different rates.  What is left is rather like a hardboiled egg with the top cut off:  the egg yolk is the eroded core and the egg whites are the inward facing slopes of the North and South Downs.  The Pent Stream is fed by springs which percolated through the chalk of the North Downs forming streams which then eroded the soft clays now exposed at the foot of the Downs.  The Pent is formed from several such streams, which met south of here, and slowly carved their way through the clay valley and into the sea.

Fresh water allowed for human habitation.  The main source of the Pent comes from a large spring situated between Cherry Garden Hill and Castle Hill**(sometimes called Caesar’s Camp) and there is some evidence to suggest that this site was occupied in Neolithic times (about 6000 to 4000 years ago).  Another possible source at Holywell Coombe, between Castle Hill and Sugar Loaf Hill, provided water for an important early Bronze Age (about 4000 years ago) settlement with ‘round houses’ trackways and fields.***  Later settlements developed on the banks of the stream which created a fertile plateau between the Downs and the sea.  This neighbourhood, Foord Valley, was very fertile and given over to orchard as can be seen from the engraving.

The source streams can be found but their flows have now been diverted under the M20.  The Pent can still be seen from the bottom of the garden at the Red Cow Pub but the main course now runs through a culvert to the Harbour.

*Image taken from the forthcoming Folkestone – the arrival of the Viaduct, by Patrick Marrin and John Middleton, Marrin’s Bookshop 2014

Photograph of the view down Culvert 14, Tontine Street

3B Junction Foord Road and Tontine Street

Grid Ref TR22916 36272

Since the severe flood in August 1996, the Environment Agency have  maintained a watching brief on the Pent Stream and its tributaries.  As part of  this process, culverts are inspected regularly and trash screens cleared to  maintain the flow of water and to ensure that any overflow is discharged into the  harbour and not into the surrounding area.

The second water tower in the Penthouses series sits over an old inspection  chamber, from where this photograph was taken.  From this and other vantage points, it is possible to see old structures including bridges over the Pent Stream  and the old arches forming part of the Victorian culvert system.  The strength of  flow and proximity of the Pent Steam can be appreciated from the photograph.*

As the Pent Stream continued on its course to Folkestone, the valley it created narrowed and deepened.  The Pent reached the sea at a narrow tidal inlet, protected on either side by steep cliffs.  The estuary created by the Pent Stream, together with the tidal inlet, provided moorage for boats but slowly the combined action of silt deposits and local currents created a shingle bar across the estuary and also silted the upper reaches of the inlet.  The upper area gradually became a stagnant marsh and a repository for rubbish.

Although the upper reaches of the inlet became unusable as a harbour, the Pent Stream still flowed with sufficient vigour in the early seventeenth century to power a mill next to Bull Dog Lane (later Foord Road South) and sometime between 1628 and 1782 another mill was built downstream on Mill Lane (later Grace Hill).**  A survey of 1782 shows  a bridge across the Pent Stream, called appropriately “New Bridge”,  not far from this spot.

*Jo Kollnberger, Technical Advisor, Flood & Coastal Risk Management, Environment Agency
**An archaeological excavation at Payers Park, off Mill Bay, Folkestone, Shepway Kent, Canterbury Archaeological Trust, 2014, pp. 4-6


3C Folkestone Quarterhouse, Tontine Street

Grid Ref TR23051 36136

Before muf Architecture/Art began their rejuvenation of Payers Park, the Canterbury Archaeological Trust undertook a

Mill Bay, black and white photograph from 1930’s.  Collection Alan F. Taylor

Mill Bay, black and white photograph from 1930’s. Collection Alan F. Taylor

community archaeological excavation of the site, which has contributed to our understanding of the history and archaeology of the Pent Stream and its surroundings.*

Sometime between 1628 and 1782 a new larger mill was built on the south-west shore of the tidal inlet at the mouth of the Pent Stream.  Access to this mill was via the appropriately named Mill Lane (later Grace Hill), which if you have visited Yoko Ono’s Skyladder in the Libarary, you will know is very steep.  A more direct route was needed from the High Street (now known as The Old High Street) along the edge of the inlet and up to Mill Lane.  When the new road, called Mill Bay, was constructed sometime between 1698 and 1782 it followed the gradual curve of the valley of the Pent Stream.   A terrace was cut into the steep sloping side of the valley and a masonry wall was built to support the new road surface.  This retaining wall is clearly shown on a survey of the town dated 1782 and was observed during a watching brief by Canterbury Archaeological Trust in 2007.**

The construction of the water mills and the new route called Mill Bay was part of a process of industrialisation.   The marshland which had formed in the upper reaches of the Pent Stream inlet was slowly built over and the area became urbanised.  Mill Bay developed gradually with housing and light industry along its route.

If you stand with the Folkestone Quarterhouse at your back, you can see Mill Bay and the steps up the The Old High Street to your left and leading towards Grace Hill to your right.  When Tontine Street was built, Mill Bay was no longer an important thoroughfare and by the time of the photograph had degraded into a slum.

*An archaeological excavation at Payers Park, off Mill Bay, Folkestone, Shepway Kent, Canterbury Archaeological Trust, 2014, pp. 4-6
**Linklater, A. 2007 An archaeological watching brief during mains drainage diversion at 45-49 Tontine Street and Mill Bay, Folkestone, Shepway, Kent. Unpublished report by Canterbury Archaeological Trust.


Black and white photograph showing timber post and planked retaining wall of the west side of the early harbour.  Black and white photograph courtesy Canterbury Archaeological trust

Black and white photograph showing timber post and planked retaining wall of the west side of the early harbour. Black and white photograph courtesy Canterbury Archaeological trust

3D 9-11 Tontine Street

Grid Reference TR22916 36272

If you stand with your back to Penthouse 3D and look across the street you can see the Information Centre car park, Tram Road.  In November 1998 this area was excavated by Canterbury Archaeological Trust in advance of proposed sewerage works.  Here the Pent Stream and another stream named Martha’s Dyke flowed into an area known as Old Sea Gate.

Written sources from the twelfth to the fourteenth centuries indicate that Folkestone was a member of the Cinque Ports Confederation, although only as a limb to Dover, and was obliged to supply ships and men.  Later in the fifteenth century, wills show that there was a thriving fishing industry at Folkestone.  Together this information suggests that there was a sheltered harbour available but nothing was known about where it was situated.

The excavation of the car park site revealed a form of land reclamation and the partial infilling of the water channel on which a metre thick stone wall and cobbled work surface had been constructed.  It is possible that this is a seawall wall with a cobbled quayside by the mouth of the Pent Stream and if so is the first physical evidence for the site of Folkestone’s medieval harbour. *

If you now walk to the end of Tontine Street and turn to your right, you are on the site of another excavation in 1999.  Here deep excavations revealed the early course of the Pent Stream and associated silt deposits.  Timber piles and planking were found running parallel to old South Street.  This almost certainly forms a retaining wall to South Street with the Harbour to one side and the hillside to the other.  (In the photograph, the sea would be to the left).  It was against this structure that ships would moor to unload or load.  The timbers were dated by their tree rings to between 1625–1650.**

A stone bridge spanned the inlet and its remains were found opposite at the junction of Tontine Street and Harbour Way.  A late seventeenth century manorial estate map shows open water extending from this stone bridge at the bottom of The Old High Street as far as the present harbour: confirming that the inlet below the bridge was still used as a harbour.

Later evidence shows that the harbour had silted up by the mid eighteenth century.  The action of silt deposits from the Pent and local currents created a shingle bar across the estuary which blocked the harbour and allowed silt deposits to build up behind it.  The harbour shifted further south and the land behind was infilled and developed until eventually the present harbour was built in 1843.  Tontine Street was constructed to link the new harbour with the expanding town and the Pent Stream was realigned through a new brick culvert.  The Pent Stream had disappeared.***

*Canterbury Archaeological Trust, Annual Reports 1998-1999, No 20 Tram Road Folkestone, John Willson.
** Canterbury Archaeological Trust, Annual Reports 1999-2000, No 24 Harbour Street, Folkestone, John Willson.
***An archaeological excavation at Payers Park, off Mill Bay, Folkestone, Shepway Kent, Canterbury Archaeological Trust, 2014


Pent Stream Outflow into Folkestone Harbour.  Black & white photograph from the collection of Alan F. taylor

Pent Stream Outflow into Folkestone Harbour. Black & white photograph from the collection of Alan F. Taylor

3E Pent Stream Outflow, Folkestone Harbour

Grid Ref TR 23239 35982

The Pent Stream flows in a south-easterly direction through the Foord Valley to its outlet into the sea at Folkestone Harbour.  The channel has been heavily modified as a result of urbanisation and the majority of the course has now been built over.  It is difficult to appreciate that the Pent Stream is classified as a Main River by the Environment Agency and that its flows can cause flooding.

The Pent Stream used to meander between the buildings of South and Beach Streets until Harbour Street, the harbour wall and slipway were constructed during the harbour development of nineteenth century and it was constrained.   The sluice gate was operated by harbour workers and was used to allow the build up of water to escape.

As the Pent Stream empties into the harbour, it brings with it continuous amounts of silt, which contribute to the infill of the Inner Harbour.  Before the harbour was developed, men were required to clear the harbour mouth by hand and the stones and silt were removed by horse and cart.

The prevailing south-westerly winds wash material along the south coast in an easterly direction and this action, together with the silting from the Pent Stream bring deposits towards the harbour mouth.  At the same time, Kent has been slowly sinking into the sea and much of the coast has been worn away.  (This is most evident on Wear Bay, where parts of the Roman Villa have now disappeared).   Geological evidence suggests that the inlet created by the flow of the Pent Stream was once protected by steep cliffs, which might have provided a vantage point for early inhabitants.


  1. Posted by Looking about the Folkestone Triennial | The Mind's Lost Continent on October 11, 2014 at 4:50 pm

    […] Diane Dever & Jonathan Wright’s Pent Houses found about the town make one aware of the history and geology of the area, considering the Pent Stream that now runs deep beneath the concrete of the streets and caused a flood back in 1996. There’s quite a detailed and fascinating explanation behind where each water tower is located on the Triennial’s site. […]

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