Pic: Diamond Geezer
Short notice, I know, but if you are in the Watford area tomorrow (Saturday 9 September) you might like to visit this important site. This is the model dam which was built in the grounds of the Building Research Establishment (BRE) in Garston, near Watford. The construction took place with great secrecy in the winter of 1940–41, two years before the Dams Raid actually took place. On their own initiative, BRE scientists and their colleagues at the Road Research Laboratory (RRL) in Harmondsworth had been discussing possible ways of attacking the German dams before the involvement of Barnes Wallis.
Wallis was put in touch with the BRE and RRL team, and it was agreed to build a 1/50 scale model of the Möhne Dam on a secluded part of the Garston site. The very informative article on the BRE website tells the story:
The model, which survives today at the centre of the now enlarged BRE site, was built in seven weeks between November 1940 and January 1941. Temperature records from the time show that the winter was very cold, with daytime temperatures close to or below freezing over much of this period, and photographs show snow on the ground.
To conceal its identity, the model was referred to as ‘Weir No. 1.’ in the records. These show that work at the site started on Monday 25 November 1940, when the area was excavated to widen and deepen the stream, and to prepare an area for the concrete base of the dam. The foundation concrete was poured on 29 November, and the two towers of the dam were cast in situ the following Monday. The side wings [were] completed shortly after this. To allow the model to be built across the stream, a pipe was placed in the foundation to carry the water beneath the centre section during its construction.
Having built the model, the scientists then proceeded to try and blow it up. The dam was badly damaged during these tests, and further experiments were carried out elsewhere. However, because it was repaired in the 1960s this is probably the only place where Dams Raid test infrastructure remains in place and viewable by the general public. As such, it was scheduled by English Heritage in 2002 as being not only of ‘national but also international importance’. (In later tests in May 1942 the Nant-y-Gro dam in Wales was also blown up, but it is still viewable in its damaged state.)
To get a flavour of what is also viewable at Garston, read this account of last year’s open day by Diamond Geezer. Hat tip to him for the post alerting me to this event, and also for use of the photograph above.