Know what you mean Steve but it's hard to get away from. However, the day itself should make the silly tourists run for cover for a while

Most of the pubs in the immediate vicinity (as visited today) only open at 12.00, (and no special arrangements for Monday

) so I might suggest an initial meeting place as the Argyll Arms which is very close to Oxford Circus undergerground station, and opens at 11.00. You wont get any tourists in there at that time!
As for a suitable retiring place, there are others to be had, but I'd welcome any suggestions. Wardour Street isn't too far away, but if we have to plan for others who get lost, then something closer might be a better idea. What think you?