The Government does have estimates for the number of workers from Romania and Bulgaria who could come to the UK once restrictions are lifted - but it is currently refusing to tell the rest of us while it decides whether revealing the figures would be in the public interest.

The Department for Communities and Local Government has confirmed that the information exists.

But responding to a Freedom of Information request asking for the numbers, an official said: "Your request . . . raises complex public interest considerations which must be analysed before we can come to a decision" on whether to release the numbers.

More than 50 senior Conservative activists, including chairmen or deputy chairman of the Birmingham Ladywood, Edgbaston and Erdington constituency associations, have written an open letter backing same-sex marriage.

Senior members of the Stourbridge and Halesowen & Rowley Regis constituency associations in the Black Country have also signed the letter.

There has been a lot of publicity about a letter signed by 22 current and former chairman of Conservative constituency associations asking the David Cameron to delay or scrap the proposal.

But senior Conservative activists who back the proposals, to be debated tomorrow evening (Tuesday February 5), have now spoken out.