I think they can do it Litebulbs i.e. make everyone redundant and re-hire on different contracts. It's what Aer Lingus threatened in Ireland, the basis and logic is that the original contract, therefore the original position no longer exists. This then meets the UK redundancy condition that the position you were hired for no longer exists, as the position is defined by law in the contract. BA could also argue collective redundancy due to reorganisation and reallocation or work. It can't be deemed unfair if everyone was made redundant.