National Express could have survived as an independent company if it had better managed its relationship with the Department for Transport, its former chairman has said.

The comments come as the troubled bus and rail operator prepares to accept a £765m bid by a Spanish-led consortium. The Spanish Cosmen family, which owns 18.6 per cent of the group, and private equity firm CVC have until Friday to complete the due diligence and either make a 500p per share offer or walk away.