National Archives HW 13/38
Report CX/MSS/OPD 1108
All times British Summer Time
GAF Operations in support of an incoming Japanese submarine …
Escort by ZG 1 was provided by groups of 8 aircraft airborne [at 0630, 1100 and 1545]
A/c of the first group (of which one was certainly destroyed) do not seem to have broken wireless silence …
[on the second operation] A/c 'A' of the Stabsstaffel signalled '2 enemy fighters' at 1704 and is presumably identical with the a/c shot down by 2 Mosquitoes of 10 Group in 45º N, 3º 40' W at this time. (A/c was unsuccessfully called 1704–1829) … Do 24 and He 177 a/c were operated on a sea rescue search, with what result is not known. Of the remaining a/c, 'I' of the first Staffel broke off with engine trouble at 1722.
From the third operation all a/c appear to have returned to Mont de Marsan.
Alex Crawford's book 'Shipbuster: Mosquito Mk XVIII "Tse-Tse", An operational history' (MMP/Stratus, 2008) puts the Tse-Tse claim at around 0920 and says that 7./ZG 1 lost a Ju 88 at 0924. I don't have my copy of Chris Goss's 'Bloody Biscay' to hand at the moment.