The Queen's Christmas message in 1968 was changed following pressure from senior officials in Harold Wilson's Labour government, it has emerged.

References in the broadcast to Britain's "economic difficulties" were dropped, reveal official documents made public for the first time.

And other documents also released to the Public Records Office under the 30-year rule show that the Wilson government was concerned that the 20-year-old Prince Charles was being influenced by Welsh nationalists.

The draft text for the Queen's Christmas broadcast in 1968 had for the first time been written by the monarch and the Duke of Edinburgh, rather than by an official outside the royal household.

The papers show that the broadcast was raised with Mr Wilson - who was sensitive about the government's economic record following the devaluation of the pound - by an official.

The official wrote: "We do not usually seek departmental advice on The Queen's Christmas broadcast. But I suggest that the content of this one is such that we ought to ask the Foreign and Commonwealth Office to look at it."

Mr Wilson agreed, writing on the letter, "Yes, HW".

The draft was then sent to senior diplomat Sir Paul Gore-Booth, who said the draft text was "quite unexceptionable".

But it was revised so that one part was changed.

It had said: "Every individual and every nation have their problems. Some are more pressing than others. Britain is not the only Commonwealth country contending with serious economic difficulties.

"Fortunately there are others who are enjoying better times, and this is certainly the moment for us all to do our utmost to help each other."

This became: "Every individual and every nation have problems, so there is all the more reason for us to do our utmost to show our concern for others."

The following year, in what may have been a hint of royal displeasure, the Queen announced the traditional broadcast was being dropped in favour of televised coverage of the Christmas Day service at St George's Chapel, Windsor.

The papers also show that there were concerns that ex-Cabinet minister George Brown might be invited to functions during US President Richard Nixon's visit to Britain in 1969.

Mr Brown, formerly Secretary of State for Economic Affairs and Foreign Secretary, had stormed out of the Cabinet the previous year and had reputation for drinking and erratic behaviour.

A senior official at the Foreign Office wrote to Edward Tomkins, British charge d'affaires in Washington, a week ahead of the visit, saying that the prime minister and the foreign secretary had agreed that the idea of inviting Mr Brown to functions during the trip "should not be pursued".

The records also show that Mr Wilson wanted to sue the BBC after David Dimbleby said on air that the press and public would be kept "fully in the dark" about discussions during President Nixon's visit, though no action was taken.

The government papers also underline the Wilson government's misgivings about the Anglo-French Concorde project, with the prime minister telling a committee that "the Concorde project should never have been started".

But there were fears that the government would be taken to the International Court if it dropped out.

'Dare-devil'

The papers also reveal that the government was worried that American foreign policy under President Nixon would favour France at Britain's expense.

But it appears that Mr Wilson and President Nixon got on well, with the prime minister relating talks with the US leader about Russia: "The president spoke almost mischievously, almost like a dare-devil, on this theme. He wanted to try the Russians out a bit. He agreed with my phrase that there were worse ways of trying to get a woman than by playing hard to get."

Mr Wilson in turn told President Nixon how, on his visits to the Soviet Union, Russian Prime Minister Alexei Kosygin would sometimes speak to him with "considerable indiscretion" when they were alone together.

Also revealed in the papers are Harold Wilson's anger when he discovered that the government had given £1,432 to research into why men preferred women wearing mini-skirts - one of the enduring images of the "swinging sixties".

Mr Wilson wrote: "If this is so valuable to these vast industries why do they not pay for it?"

Other revelations in the papers include;

Cabinet in-fighting over plans to curb the power of the unions. Ministers feared the controversy over the industrial relations White Paper, In Place of Strife, could even lead to the overthrow of Mr Wilson.

Concern over security at the Investiture of the Prince of Wales, with Mr Wilson saying he was troubled by "the persistence of the more extreme forms of Welsh nationalism".

The lack of intelligence about the IRA at the outbreak of "the Troubles" in Northern Ireland.