Andrew Grice: Whisper it, but Whitehall is already preparing for a change at No 10

"I know I'm pissed, but first I want to ask one question," John Prescott told the Shadow Cabinet, fresh from The Spectator's annual parliamentary lunch. "Why do I want some permanent cabinet secretary telling me things? I'll find out soon enough when we're in government." He was then escorted out of a briefing with Sir Robin Butler, the Cabinet Secretary. It was 1991, and Mr Prescott had to wait a little longer to "find out".

Today, contacts between the Opposition and Whitehall are more friendly, serious – and sober. Well away from prying eyes, the Civil Service prepares quietly and furtively for what would be only the third change of government in 31 years.

Officials do not take a Conservative victory next year for granted. They have made mistakes before. In 1992, one Downing Street aide suggested that Norma Major start packing up her possessions in case her husband lost. She refused and he won.

Buckingham Palace and the Cabinet Office discuss discreetly what would happen in a hung Parliament, which cannot be ruled out. The ground rules: keep the Queen out of it; the politicians must sort it out.

Yet you can almost sniff the expectation of change in the Whitehall air. Meetings between permanent secretaries and Shadow Cabinet members last longer and are much more business-like than in 2001 and 2005. "Then, we went through the motions about our policies and then had a cup of tea and a gossip," recalls one Tory frontbencher. This time, Whitehall senses it is for real. "The Civil Service has given up on Labour and Labour has given up on the Civil Service," claims one shadow minister. "Exactly the same happened to us before 1997."

Ministers deny it, praising the professionalism of neutral officials who must serve only one master – and it is still Labour for now. But some ministers admit the wheels now turn slowly on projects the Civil Service doesn't like, and that some senior officials don't bother to have regular meetings with them. "We know what they are thinking," says one cabinet minister.

Formal talks between the Tories and Whitehall are friendly but necessarily tentative. Civil servants can "listen" to an Opposition's proposals but cannot "advise", even if they think its policies are unworkable. There are some informal contacts. Senior officials "accidentally" bump into shadow ministers at social functions.

Both sides eye each other up. The Tories wonder whether too many officials have caught Labour's "big government" bug. Officials, most of whom were not around when the Tories last came to power in 1979, ask whether Tory ministers would speak the "language of New Labour". They wonder what David Cameron meant by his call this week for civil servants to become "civic servants". Some try to please their likely new masters. "We mustn't look like [pro] Europe nutters," one told colleagues.

The Tories claim they would be better prepared than any other incoming administration. All Oppositions say that, but the Tories might just be right. An implementation unit, under the shadow Cabinet Office minister Francis Maude, beavers away. Shadow ministers draw up detailed plans not for their "first 100 days" – an inevitable media obsession – but their first 365. (Whether they would have enough money to implement them is another matter).

The Tories, understandably, are reluctant to discuss their plans. Mr Cameron stamps on any hint of what Whitehall calls "curtainitis" – measuring the Downing Street curtains before the election is won. Taking the voters for granted could make victory harder.

Yet perhaps the Tory leader could be a bit more open about his preparations for government. He believes that Tony Blair expended so much energy on winning that he didn't really know what to do once he got there. The Tory implementation strategy is designed to learn from that mistake.

Mr Cameron could be more effective in power if he broke with some traditions. A sensible reform blueprint was published this week by the independent Institute for Government. The authors, journalist Peter Riddell and historian Catherine Haddon, pointed out that Britain has the quickest transitions in similar democracies. A new prime minister, exhausted after weeks of campaigning, takes over on the morning after the election, normally names a Cabinet that day and rushes out a Queen's Speech within two weeks. It is usually done on the hoof; Mr Blair had not finalised his Cabinet when he arrived at No 10.

The study suggested ministerial teams should be named at a more leisurely pace and the Queen's Speech take place a month after the election. It proposed that more shadow spokesmen should keep the same briefs in government; in both 1979 and 1997, two out five moved to a different portfolio. Ministers new to a subject were often less successful and had to be reshuffled later.

Other proposals, such as earlier and wider contacts between the Opposition and Civil Service, would require Labour's blessing but I believe that it would make sense to act on them now. Labour was more effective – for example, in David Blunkett's education reforms – when Whitehall geared up in advance. But no government wants to admit the possibility of defeat.

Better preparation in opposition would ensure better government. Only seven of the 32-strong Shadow Cabinet have been ministers, and only three (Kenneth Clarke, William Hague and Sir George Young) full cabinet ministers.

A lot could change. Probably, not much will. Mr Cameron has an election to win first. Britain will continue to change governments on the hoof.