Don't know if this thread is still being read but I thought I'd write just in case it is still 'live'. A legally binding contract is created after formal acceptance of an offer of employment the contract. Boradly speaking, neither future employer nor employee can withdraw from that contract without breaching it, irrespective of whether employment has commenced or not. That said, I am sure may employees do, without repercussion (as, in relation to a junior hire especially, it is simply not worth the employer's time or money going after the culprit). I would imagine that only the most shady of employers are likely to refuse employment to someone who has accepted their offer. Thanks