Sir John Sawers is currently the UK's ambassador to the United Nations
The UK foreign secretary has defended the next head of MI6 after details of his private life were removed from social networking site Facebook.
David Miliband denied security had been compromised after the wife of Sir John Sawers posted family photographs and details of their children and home.
Mr Miliband told the BBC: "You know he wears a Speedo swimsuit. That's not a state secret."
Some Tories said the disclosure was damaging and Lib Dems want an inquiry.
However, other senior Conservatives have played down the risks.
Sir John is the UK's ambassador to the United Nations and is due to take up his new post in November.
The Mail on Sunday said information published on Facebook included the couple's friendships with senior diplomats and actors, including Moir Leslie from BBC Radio 4's The Archers.
David Miliband: "For goodness sake, let's grow up"
Lady Sawers revealed the location of the London flat used by the couple and the whereabouts of their three grown-up children and of Sir John's parents, the paper said.
She had not imposed privacy protection on her account, allowing any of Facebook's 200 million users in the open-access "London" network to see the entries, it added.
The coverage also featured several family photographs, including some of Sir John wearing swimming shorts on holiday.
But Mr Miliband told the BBC's Andrew Marr programme: "Are you leading the news with that?
"The fact that there's a picture that the head of the MI6 goes swimming - wow, that really is exciting.
'No state secret'
"It is not a state secret that he wears Speedo swimming trunks, for goodness sake let's grow up.
"He is an outstanding professional who will do a really good job in an outstanding organisation."
Shadow business secretary Ken Clarke also dismissed the potential security implications of the information, saying he "very much doubted" national security was jeopardised.
"In the old days we used to keep the name secret, all photographs were banned and I never really believed that the Russians didn't know who the head of MI6 and MI5 was," he told Sky News.
"I suspect that the enemies of this country do not wholly rely on the Mail on Sunday and Facebook for their information so I personally would get a little more calm," he added.
Former Prime Minister Sir John Major said the issue had been "overblown".
He said: "I know John Sawers. He's a very able man, he's a very able appointment. It's pretty unfortunate that this has happened, I think that is true.
"But I think when you're faced with leaving Iraq possibly too early, huge problems in Afghanistan, the mess in Pakistan, the depth of the recession, I think this falls a long way below those."
They spoke out after Conservative MP Patrick Mercer, chairman of the counter-terrorism sub-committee, told the BBC it raised worrying issues.
He was concerned about the revelation of "the location of flats, transport details, movement details, of an individual who is our most senior counter-terrorism officer abroad".
He added: "A great deal of taxpayers' money has been spent over the past several decades making sure he and his family are protected from security compromises.
"Well, it doesn't seem to be very relevant any more, does it?"
Liberal Democrat foreign affairs spokesman Edward Davey also claimed the disclosure had the potential to damage the security of Sir John's family.
"We would be negligent if there wasn't an internal inquiry into the security implications, not just in relation to MI6 but to Sir John and his family," he said.
Lady Sawers had no Facebook privacy protection, the Mail on Sunday says
"We need to be reassured that this has been considered properly and there is nothing we need to worry about as a result of this."
Sir John is due to replace Sir John Scarlett as head of the overseas Secret Intelligence Service (MI6).
He has been the UK's Permanent Representative to the UN since 2007.
Before that he was political director at the Foreign Office, an envoy in Baghdad and a foreign affairs adviser to former Prime Minister Tony Blair.
He was in that post from 1999 to 2001 and was involved in the Kosovo conflict and Northern Ireland peace process.
Elsewhere overseas he worked in the British embassy in Washington, as an ambassador in Cairo and to South Africa from 1988 and 1991 when apartheid was ending.