Just got back from lunch with my friend. She says that her dh (BA pilot) thinks that lots of people won't actually strike because they won't want to be out of pocket.
Apparently, only about 1000 people were balloted to strike and all these were more senior crew (who have most to lose) and those who are due to take voluntary redundancy (how he knows this, I don't know!). They were only asked whether they wanted to vote for strike action, not when or how long for.
BA want to change their pay sructure so that the cabin crew get a higher basic salary but less allowances when away and they want to amalgamate the long/short haul flight crews so that they don't have two separate groups. Gatwick have mostly shorthaul flights so they don't mind as much but heathrow have more long haul flights and these crews do not want to lose their longhaul allowances by having to change to short haul (apparently, there is also hardship pay to fly to miami as no-one wants to fly there, which flight crew do not get).
Friends dh thinks that lots of people will work and not strike and if anyone strikes, there is a risk of being sacked as legally they should not be striking according to court case recently.
So, all is not lost, flights may well still be running - they have a website for crew to log in and show they will be working anonymously i.e. with an id code, so hopefully BA can plan.
BA will favour running the long haul flights over short haul as these are more difficult for passengers to alter and find alternatives for.
Not sure if this makes it any clearer or not!