They are the ultimate strange bedfellows - Northern Ireland's Deputy First Minister Martin McGuinness and Queen Elizabeth II.

But McGuinness raised some serious laughs - and quite a few eyebrows - when he revealed to a packed conference that he had slept in the Queen's bed at Hillsborough Castle.

McGuinness, a Sinn Fein minister, startled guests with his revelation during an after-dinner speech he gave at Hillsborough Castle, the Queen's official residence in Northern Ireland.

Hillsborough, built in the 18th century, was the epicenter of the political talks in 2010 over the transfer of policing powers to the Northern Assembly at Stormont from Westminster.

According to the BBC McGuinness told over 150 delegates at a gala opening of last week's international business conference that Sinn Fein was assigned the Queen's bedroom during days of negotiations with the Government.

'We were lucky enough that we were allocated the Queen's bedroom,' he said, leading to guffaws from the audience.

'I do not want you to tell anybody…' he continued. 'But I had a snooze in her bed. She was not in it, so no scandal attached.'

The reaction of some of the unionists politicians in the room, including First Minister Peter Robinson and Secretary of State Theresa Villiers, was not recorded, despite the presence of TV cameras in the room.

The Queen's spokesperson had no comment on the matter.