Back to Sid's filmography: Whilst sorting through some BSA archive material, a box of 16 mm film clips were found together with some notes. These were passed across to Sid Perou, who identifying them as being very fragile, negotiated with the Yorkshire Film Archive that they be digitised, with the YFA retaining the originals for safe-keeping. They turned out to be the original 1953-1954 experiments by the British Speleological Association, led by Eli Simpson, to make a film about limestone caves in the Yorkshire Dales, called Birth of a Yorkshire River. As originally conceived, it was a grandiose project which included resurrecting the waterfall at Malham Cove using pumps and laying two miles of hoses down the Watlowes Valley, and powering large underground lights with an even larger generator which needed to be transported to the cave entrances. But as the technical and cost constraints became apparent, the project was abandoned and all that remains are these rushes and the notes. Using his technical know-how and a lot of detective work, in 2012 Sid unravelled the story and made this superb documentary on the project, first shown at the BCA's Hidden Earth conference. More information can be found here.