Michael Gove, the Justice Secretary, will chair the campaigning committee of Vote Leave, I understand. And the Labour MP Gisela Stuart is expected to chair the formal board of Vote Leave.

Gove will therefore in effect become the head and most visible politician in the most prominent of the two lobby groups campaigning for the UK to quit the European Union.

In that sense Gove will be put into direct confrontation with the Prime Minister, his old friend - and with whom he still sits in the cabinet.

The appointment of Gove and German-born Stuart, to be announced in the next day or so, is a vital organisational change for Vote Leave, as it endeavours to be anointed by the Electoral Commission as the so-called designated lobby group for leaving the EU.

Vote Leave will hope the combination of leading Tory and Labour figures at its head will persuade the Commission that it is broadly enough based to become the official Leave campaign - and be permitted to spend up to £7m in the final stages of the referendum battle.

Labour MP Gisela Stuart is expected to chair the formal board of Vote Leave. Credit: Labour Party/PA Images

It is in a life-or-death struggle for the designation with Grassroots Out, which has the backing of UKIP and some well-known populist politicians, such as George Galloway - but which does not contain any cabinet ministers.

Stuart will replace the former Chancellor of the Exchequer Lord Lawson as chair of Vote Leave. When Lawson agreed to be chairman in February, he was explicit that he would hold that post for just a few weeks.

Mr Gove has today been the subject of widespread gossip that he was the source of the Sun's splash story that the Queen favours Brexit - since he was at the lunch cited by the Sun during which Her Majesty was allegedly critical of the EU.

Buckingham Palace has complained to the press watchdog IPSO that the Sun's story was misleading.

Michael Gove and his wife Sarah Vine at the wedding of Rupert Murdoch and Jerry Hall. Credit: Yui Mok/PA Wire

Gove is widely regarded as one of the brainiest and best-connected Tory ministers. A former journalist, he is a friend of Rupert Murdoch and recently attended his wedding to Jerry Hall.