"....what must it have been for the boys and girls in Lash and elsewhere?"
To be honest "variable". Some post seemed to get to some people quite quickly whilst others were less lucky. Over Christmas we received a great deal of post (a veritable torrent) but that was due to the generosity of the British Public and it wasn't representative of the normal level of mail coming into theatre. I'm still amazed how much was shifted and not just to the hubs but up to where it was really needed, in the FOBs. Average time for post here now? - I guess 10 to 14 days. Whoops, that was nearly a "line to take"!