John,
My impression (still haven't seen all the files, including the enquiry) was that the escort dispersed its forces to pin down individual U-boats rather than in maintaining a close guard around the convoy. This was common practice in the early part of the war and often 'harmless' to a convoy if used against lone U-boats or small groups, especially in daytime. In this case it was acknowledged to have given the advantage back to the attackers. It is also clear that, once the convoy was spotted, casualties were inevitable but the escort commander(s) lacked the experience to break up the co-ordinated pack tactics used against them.

I will wait until I see the rest of the files, but the timing of the shift in escort tactics (including instructions to stick with the convoy) was around this time, so may have been based at least partly on experience of OG71.

In 'Nightmare Convoy' Lund & Ludlum imply that fate of OG71 was the reason for the Admiralty change of tactics, but the wording is slightly cautious so I hope to clarify this point.

Bruce