"BALPA would not allow a large number, a guess might might be a max of 20 of the 120 places available at the moment.'
BALPA have no say in where new entrants are posted. BA has every right to post DEPs to whichever fleet they want and BALPA recognise this.
This has caused unhappiness in the past as LGW SH (and LHR SH for that matter) have seen new entrants go straight to LH.
When it comes to bidding for a different seat / fleet everyone's seniority is based on Date of Joining (and not being frozen etc) so they are at no advantage there.
Can't belive I'm contributing to this thread - as always it's full of non-BA people proclaiming they know how BA works.