The stand-off between National Express and its largest shareholder erupted into open warfare on Wednesday after it emerged that the Cosmen family will try to rally shareholders to block the company’s £360m cash-raising exercise.

The bus and rail operator needs more than 50 per cent of shareholders voting at the EGM on November 27 to support the rights issue. But the Cosmen family, which holds 18 per cent of the stock, is campaigning to put the cash-raising exercise on hold.