A conference convened to debate the institution of marriage almost had to be cancelled after a second venue pulled out at the eleventh hour.

Christian Concern organised the conference in light of the Government's current consultation on legalising gay marriage.

Speakers Phillip Blond, Cristina Odone, Professor Brenda Almond and Brian S Brown of the US campaign group, National Organisation for Marriage, were invited to debate whether a compelling case could be made for traditionally defined marriage.

The conference had originally been booked at the Law Society but had to be moved after the organisation cancelled the booking on the grounds that it did not fit with its diversity policy.

It was then re-booked at the Queen Elizabeth II Conference Centre in Westminster. However, Christian Concern was contacted late on Tuesday afternoon - the day before the conference - and told that the event had been deemed inappropriate for the conference centre as it did not fit with the values of the government agency that runs the facility.

Overnight legal efforts to halt the decision failed and the conference had to be moved to an alternative venue at the last minute as delegates were due to arrive before a court could sit.

After a hasty search for alternatives, the conference was finally able to go ahead as scheduled at the nearby Thistle Hotel.

Andrea Minichiello Williams, chief executive of Christian Concern said: “It is extraordinary that at a time that the Government is consulting with the public about the legal definition of marriage, a Government owned venue has suddenly decided that a conference examining the issue can not be held.

"A climate of fear and intimidation is being created which is suppressing proper, free discussion of these vital issues. This should be of concern to all who care about the vitality of our democracy.”