Ashley Highfield, the BBC's director of future media and technology, is leaving the corporation to launch a joint online video platform for the BBC, ITV and Channel 4 which the broadcasters hope will be "a Freeview for the internet".

Mr Highfield's move, expected to be announced today, will create a vacancy for the most senior position in the UK's digital media industry. The post controls a budget of £400m, or one eighth of the annual £3.2bn licence fee funding.