Sir Gus O'Donnell Warns The Union Will Be Hard To Hold Together

Sir Gus O'Donnell, the outgoing head of the civil service, has issued another parting shot before his retirement at the end of the month, this time suggesting preventing the breakup of the United Kingdom will be an enormous challenge in the coming years.

With Scotland expected to hold a referendum within five years on either full independence or substantially increased devolution for the parliament in Edinburgh, Sir Gus says in a letter to the Daily Telegraph: "Over the next few years, there will be enormous challenges, such as whether to keep our kingdom united."

It's the second time in a week that Britain's most senior civil servant has spoken out ahead of his retirement, prompting some to question whether his statements are appropriate.

In his Telegraph letter Sir Gus said the Civil Service needed to overcome its "cultural inertia" and take a leading role in driving economic recovery.

"It is not enough now for the Civil Service simply to respond to a dampened economic climate: it needs to become a central part of its recovery and growth," he wrote.

Earlier, in an interview for Channel 4 News, Sir Gus disclosed that Whitehall had carried out contingency planning in case the coalition breaks up - although he said he believed it would run its full course to 2015.

"My reading of the coalition, the relationship between the Prime Minister and the Deputy Prime Minister, is that is probably when the next election will be," he said.

"You have to do contingency planning, but I think our main scenario is that we go through to 2015."

At the weekend Sir Gus used an interview to say that Freedom of Information laws should be changed to ensure that ministers could have open and frank discussions without worrying it would all be released in an FOI request.

Speaking on Sky News on Monday night the former Labour home secretary Jacqui Smith suggested that Sir Gus shouldn't be speaking out on so many matters, regardless of whether he was shortly due to retire. "Normally the understanding is you just get a place in the House of Lords," she said, claiming previous heads of the civil service would never have given valedictory interviews.