Details of the accident from data on the mossie.org website2 were recovered from Loch Striven and there wil be a few more in Machrie Bay in Islay. Mosquito DZ579 lost it's tail from the splash on one drop and dived into the sea at Machrie Bay, IWM has a video of it happening.
The attached image is the sidescan of Loch Striven, there are a lot still down there.
Machir Bay is the correct locaion, I was relying on my decaying brain when I said Machrie.Details of the accident from data on the mossie.org website
S/Ldr Arthur Jaques DFC & BAR was flying a Mosquito with the MAEE on 25/10/1945 on a practice `Highball` when the aircraft crashed in Machir Bay, Islay. With him was F/Lt Eric J.Saville, DFC. (Dave Earl on RAF Commands Forum) AB's 'UK Flight Testing Accidents' has this to say: 25 October 1945 Mosquito B.IV DZ579/G Sqd Ldr A Jaques DFC and Flt Lt Savin, MAEE, Helensburgh. Trials for operation 'Highball' flown from Port Ellen. Dropped a store at 30' into a rough sea. The splash caught the tail of the aircraft, the port wing broke off and the aircraft dived into the sea at Machin Bay, Islay (5546N, 0627W). 2 missing, presumed killed. Splash from drop test hit tall lost wing and dived into sea Machir Bay Islay 25.10.45 (Air Britain Serials)
Must admit I've not seen film of that accident. The more usual one to appear on the internet is of a Douglas A-26 Invader suffering a similar fate.