He has the world�s most sophisticated security technology at his disposal and has made a distinguished career keeping state secrets.

He has the world's most sophisticated security technology at his disposal and has made a distinguished career keeping state secrets.

But the new head of M16 has had his family life exposed by a widely available and simple tool: an internet social networking site.

Sir John Sawers' private life has been made public by his wife's enthusiasm for Facebook.

His wife, Lady Shelley Sawers, published intimate photographs and personal details on the site, including photographs of her husband sporting a pair of Speedo swimming trunks and she and their daughter Corinne recreating a scene from the musical Cabaret.

The embarrassing lapse in judgment comes as Sir John is due to take over as chief of the Secret Intelligence Ser- vice in November, which will put him in charge of Britain's spying operations abroad.

However, Lady Sawers' foray into the world of online networking has publicised potentially compromising details about where they live, work and holiday and who their close friends are.

Unfortunately for Lady Sawers, she failed to add effective privacy protection to her webpage, meaning her account is visible to any of the site's 200 million users.

The slip-up caused concern that the safety of Sir John's family and friends may have been compromised.

However, Foreign Secretary David Miliband dismissed calls for the appointment of Sir John to be reviewed.

Speaking on BBC1's Andrew Marr Show, Mr Miliband scornfully dismissed questions of the security breach and instead defended Sir John, who is currently British Ambassador to the United Nations, as an "outstanding professional" who is well suited to the MI6 post.

He said: "It's not a state secret that he wears Speedo swimming trunks, for goodness sake. Let's grow up.

"He was appointed 10 days ago to be the head of MI6; he's an outstanding professional who will do a really good job."

After a Sunday news-paper contacted the Foreign Office, Lady Sawers' page was immediately removed. It revealed the whereabouts of the Sawers' London flat, and the homes of their two sons, their daughter and Sir John's parents.

For the past year, Lady Sawers has kept her Facebook page regularly updated with a range of topics from parties and holidays to the health of the family pets.

On the day her husband's appointment was announced, June 16, Lady Sawers posted 19 pictures of the couple on holiday in the West Country while the following day she displayed a further 26 pictures including Sir John on the beach in swimming trunks, with his mother and posing with his wife and children.

Her internet "friends" used the webpage as an opportunity to congratulate Sawers on his new job with one relative writing: "Congrats on the new job, already dubbed Sir Uncle C' by nephews in the know!"

Codenamed C, for chief, Sir John, 53, will replace Sir John Scarlett in November. The appointment of a career diplomat to the role drew incredulity from certain quarters of the secret intelligence world.

Sir John has been the political director at the Foreign Office, the ambassador to Cairo and Britain's special representative in Baghdad.

The Liberal Democrats have called for an enquiry into whether he should be allowed to take up the MI6 post, although Conservative shadow business secretary Ken Clarke denied the incident would have grave implications. "In the old days I never really believed that the Russians didn't know who the head of MI6 and MI5 was," he said.

"I suspect the enemies of this country do not wholly rely on the Mail on Sunday and Facebook."