The son of the former Prime Minister married Sarah Russell, the sister of Viscountess Rothermere, on Thursday, after a three-year courtship, according to The Sunday Telegraph.

The ceremony was at a register office in Gibraltar, it added.

He has reportedly told his mother, Baroness Thatcher, but not his sister Carol, who is currently aboard the QE2.

Sir Mark told the newspaper: "Sarah and I knew from a very early stage that this was special and marriage had always seemed the inevitable outcome.

"We are both absolutely delighted that it's now official. We were determined to keep the day for ourselves and only had three close friends at the ceremony and they kept it a secret for us."

Sir Mark, 54, and his wife, 42, will honeymoon in the Middle East and Indian Ocean, the newspaper said.

He was formerly married to Diane, for 18 years.