Channel 4 is to air an ‘unauthorised’ TV series on the Queen – based on interviews with royal insiders – around the same time as a crucial decision by ministers on its future funding is due.

The five-part series, The Queen, was described by the broadcaster today as part-documentary, part-drama.

Scheduled to be broadcast in a 9pm slot during the summer, it will explore key events in the monarch’s 55-year reign and her relationships with figures including Margaret Thatcher and Camilla Parker-Bowles.