I would take any numbers off to BA with a big pinch of salt. Maybe 9 are working their notice, but how many are in the hold pool waiting for a start date to give their notice? How many still working through the selection? I know that's the case at my outfit (not Thomson.)
I would be interested in this if BA doesn't work out for me, except for the awful contracts on offer which means it makes better financial sense to stay where I am.