MPN11,
I don't think anyone can say for sure, that's the problem. No one knows how many of those that were on leave, off duty or sick would actually have gone on strike and the way the dates were organised, many crew would in between trips for both sets of dates. Co-incidence maybe?
The figures for LGW were more or less correct from what I saw and the LCY figures were, in my eyes, company spin. The only mainline crew at LCY that can legally strike are those doing the LCY-JFK and they are in fact LGW crew! However, this may have been put out by the company to reassure those booked on CityFlyer flights.
Unfortunately, the only way we will know for sure is if we end up with a prolonged walkout. I suspect more will work than not if the past trends are anything to go by, but until it happens, I would guess few of us would be able to say one way or the other for sure. Sorry. Not a lot of help, I'm afraid.