Perhaps a few people didn't get on and standby crew had to be called out ?
Seeing as I'm one of those subject to this audit, if I may:.... Given the state of the road system in the south east UK there's often more than a few "road commuters" who miss report, so it wasn't that (in fact it's often easier to get into London by air than by using the M ways....).
Many effected by this audit have made the point that driving into LHR/LGW can be more tiring than sitting on your backside in M class flying in from say, Manchester, ( probably less than hour block to block flight most days) but the company aren't interested in that argument. Fly in from Manchester, you must then have have 12 hours at base prior to report....drive in....well, there are recommendations but no hard rules.........
BA can monitor staff travel usage, they now feel they have a legal duty to monitor staff travel to ensure rest prior to report. They can't monitor private cars, so the car drivers can carry on as before, the "flying commuters" are getting it in the neck..
Please don't shoot the messenger......