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You will no doubt have read the pages on the history of the Lido, now here are the technical, reasons behind its decline.

It should be noted that these words are not those of Ruislip Online, instead they have been provided by Colin Bowlt and form part of a Ruislip, Northwood and Eastcote Local History Journal from 1998. You can find out more about this society here. This article has been reproduced with his kind permission, and initially opens with a reference to an earlier issue..


by Colin Bowlt

The exciting childhood memory recounted in the 1997 Journal, by Mr John Sullivan of his descent down a well being bored near the Ruislip Lido in the early 1940’s, and his query  as to whether it was connected with the recent large hole that opened up beside the Lido prompts the following account.  It is based upon letters and notes of  S.W. Hester[i], the Ruislip geologist who worked for the Geological Survey and an article that appeared in The Surveyor and Municipal and County Engineer, on 10th May 1946[ii]

The Two Wells. 

A proposal to construct a pumping station at Ruislip Common and abstract water was approved by Parliament in 1939 by the passing of the Colne Valley Water Act.  This had not been completely straightforward since in January of that year the Ruislip-Northwood Urban District Council had sealed a petition of protest against the Bill. Whilst not opposing the work the Council desired to secure certain safeguards.  It was stated that Harrow and Wembley as well as the Middlesex County Council were opposing it.  What effect this had is unknown, but the commencement of World War II probably expedited matters. 

The position of the well was in the field behind the houses on the north side of Reservoir Road as shown on figure 1.  Progress was slow owing to war-time difficulties of man-power shortage and poor quality materials, so that it was not until April 1942 that the 8 foot diameter well bottom was reached at a depth of 275 feet and the top 100 feet had been lined with steel tubes.  It had gone through 37 feet of clay, 25 feet of Reading Beds and into 213 feet of the Upper Chalk.  The trouble with the whole enterprise was that it failed to produce the hoped for yield of water.  Prior to the deposit of the Bill, consulting geologists had stated that 2.5 m.g.d (million gallons per day) was not an over optimistic estimate, but apparently with no basic reasoning in support. An initial flow of 0.4 m.g.d looked encouraging, so an addit (tunnel) was driven north under Copse Wood and then north-east under Poor’s Field, (see figure 1) to tap more of the chalk, but the yield only increased to 0.8 m.g.d.  This was eventually coaxed to 1.1 m.g.d after a total of some 300 feet of costly tunnelling.  Figure 1 shows that to go under Poor’s Field meant going beyond the Limits of Deviation of the 1939 Act.  In peace-time this would have necessitated going back to Parliament to get a new Private Bill passed, but under the Defence Regulations the Minister of Health simply issued an Order to legalise progress in June 1943.  The Order was subsequently confirmed by Parliament retrospectively in 1945. 

It was decided to sink a temporary 12 inch exploratory bore towards the northern end of Poor’s Field (see figure 1) and it was completed by August 1943.  It went to a depth of 330 feet and the results were felt to be sufficiently encouraging to justify a proper well.  However, Poor’s Field is common land, so a site for a 5 foot diameter well was arranged on land adjacent, in what was then the northern end of the Reservoir property (figure1).  The concrete capped well surrounded by iron railings, and looking like the tomb of some forgotten warrior, can still be seen beside the Ruislip Nature Local Reserve.  It was completed to a depth of 300 feet by August 1944.  A yield addit was extended under Poor’s Field as shown.  This eventually provided 2.25 m.g.d. With the 1.1 m.g.d from the first well it was decided to build a treatment works to handle 3.5 m.g.d on the site of the original boring.  The operational buildings at the site of number 1 well appeared very temporary and I can remember the chugging of the pumps in the 1950s.  It is so often difficult to recall when things actually cease.  My best estimate is that water production stopped in the late 1950s/early 1960s.  A letter dated 5th October 1977 to Mr S.W. Hester from Mr John Christie, Chief Engineer, Colne Valley Water Co. says: “It may be of interest to you to know that the combined reliable yields of the Ruislip Common and Poor’s Field wells fell far short of the hoped for 3.5 m.g.d.  When we last used them some years ago the yield was about 1.5 m.g.d.”. 

The picture to the left is A4 size and therefore will take a while to open. Click on it to enlarge.


On February 26th 1951 Mr Hester gave a lecture on swallow-holes to the Ruislip and District Natural History Society (which also included local historians at that date before the formation of the Ruislip, Northwood and Eastcote Local History Society) explaining that they were holes which appear in the ground, sometimes without warning, where chalk strata is close to the surface and cavities occurring in the chalk collapse.  He said that ten had been observed around the Reservoir in the last six or seven years [i.e. since 1944] and that three were present in Poor’s Field.  In what appear to be notes for a paper he says: “Over a period of six years I have observed nine swallow-holes along the northern and western sides of the Reservoir.  The largest of these seen in November 1944 was situated at the waters edge and a large amount of water from the Reservoir had disappeared down it.  Its dimensions were 15 feet long, 12 feet across and 10 feet deep.”  I think it significant that the swallow-holes did not occur until after water pumping started under Poor’s Field. In an article on the local geology in 1942 Mr Hester makes no mention of any such swallow-holes[iii] and I well remember the interest they were causing in the Natural History Society in the early 1950’s, as if they were still a novelty. 

An interesting reference to a possible connection between pumping water from bore-holes and swallow-holes occurs in a reply letter to Mr Hester dated 25th March 1942 from a Mr F.K. Sinclair in connection with the Eastbury Pumping Station. “... I should doubt very much if you would be afforded any information about the system there, as the Company was violently attacked in 1927 by the Watford Corporation and other bodies, alleging that the pumping at that station was the cause of the subsidence which took place about that date in Kingsfield Rd., Oxhey, when a hole 70 feet deep opened in the front garden of a house.  The petitions which were lodged against the Colne Valley Water Bill 1927/8, mainly based on this matter, resulted in the Company withdrawing the whole of the proposals in the Bill for the sinking of further wells in the valley of the Colne.”  Could this have been the reason for the siting of the pumping stations on Ruislip Common?  Mr H. Wallhouse in his article in The Surveyor about the project says, “The site was, in fact, largely dictated by political necessities, the intricacies of which are outside the scope of this paper”.   

It all happens again, with some curious results. 

In a postscript to an article in the Society’s Journal for 1991, I mentioned that because of continued lack of rain following the partial draining of the Lido in early 1990 to allow repair work in the swimming area, it had been impossible to refill it by natural means in time for a charity event in July.  Water was therefore pumped from the now disused well that penetrates 300 feet deep into the chalk under Poor’s Field.  The sound of the pump chugging away night and day continued for many days, but eventually the water-level in the Lido was up again.  Never had I seen the water so clear, clean and limpid.  The day was saved!  But the bore-hole had been activated again and in the summer of 1991 a very large swallow-hole opened up on the western edge of the Lido and swallowed-up a large amount of Lido water. 

Hillingdon Borough had let the Lido to a private company calling itself Eau Naturelle in February 1991, with a view to granting the company a 99-year lease from October 1991.  There was ferocious public opposition as the company was planning mega concerts by the waterside and was even considering organising War Games in Park Wood.  Council officers and the directors of Eau Naturelle suffered a withering attack at a public meeting held in a marquee at the Lido in August 1991.  The swallow-hole had opened up about a month before and the Council were beginning to rue their decision.  Council officers seeking a contractor to fill in the hole were given estimates of £70,000 and upwards.  To minimise costs the Council agreed to pay Eau Naturelle’s rates of £22,000, if the company would take over responsibility for the hole.  In the event the company paid David Cokeley just one pound and he did a deal with the National Rivers Authority who paid him for the right to dump clay which was being dug out of the Yeading Brook’s flood alleviation works[iv].  The site of the swallow hole is shown on figure 2. 

The low water level stopped the dinghy sailing and curtailed the water skiing and put a blight on Eau Naturelle’s plans.  The company agreed to share the costs of restoring water levels with the Council, but about this stage the Borough Engineer decided, for entirely unrelated reasons, that the level of the water in the Lido should be kept permanently low.  This was to contain a possible massive cloud burst (risk: once in a hundred years) which might otherwise flood houses which had been built downstream on the bed of the Canal Feeder.  The Feeder stream had been diverted into the bed of the Canon Brook. 

Another trouble for Eau Naturelle was that lorry loads of clay and even rubble kept being dumped in the Lido even when the swallow hole had been filled.  This was just the chance the Council were waiting for.  Eau Naturelle had breached their contract and were ordered to leave in June 1992[v].  The Lido management was put out to tender again in December 1992, but the Lido site lay derelict for a couple of years before an arrangement was made with the Whitbread Breweries in 1994 to build a family restaurant and renew facilities[vi].  In the interim the Art Deco building had not been properly protected and was set on fire in June 1993 and demolished in March 1994[vii].  Whitbread’s Waterside Restaurant opened in August 1996, faintly echoing the lines of the original 1935 Lido building. 

The former Reservoir never was allowed to fill up. The Council were too afraid of that once in a hundred year flood and the compensation implications.  The sailing boats have not returned and the muddy exposed edges have become covered with grass and developing scrub.  Things have changed, but who would guess that it all started with a bore hole. 

FIG 2  Ruislip Lido Jan 1993, showing the site of the 1991 swallow hole. 

The picture to the left is A4 size and therefore will take a while to open. Click on it to enlarge.


[i]      S.W. Hester Archive: personal possession.

[ii]     Hal Wallhouse, Genesis of a Pumping Station, The Surveyor and Municipal and County Engineer, 10th May 1946.

[iii]    S.W. Hester Archive: personal possession.

[iv]    Uxbridge Gazette: 27 May 1992

[v]     Ibid: 17. 6. 92

[vi]    Ibid: 6.7.94

[vii]    Ibid: 16.3.94  

Footnote: -

What an interesting summary! S.W. Hester was my father. 

He took a great interest in the problem of finding sufficient water in the area to supply the local needs. He was baffled by the decision to sink the well at the chosen site as the site was contra-indicated by the theory he had used to site several successful wells elsewhere. As I recall, the reason the site was chosen at all was simply that acquisition of the right to dig was easy! 

My father sited the successful well at Jacket's Lane. I recall going down in the bucket and being very impressed with the inflow. My father was also involved in providing advice that led to the clearing out of the channel of the River Pinn after the flood of 1936 or 1937.


Brian Hester

Read more about Mr Hester, buildings that crack in Ruislip and worms that turn in Harefield


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