They have made the journey from London to the Monarch's country retreat, near King's Lynn, by helicopter after feeling under the weather with what were described as 'heavy colds'.

Aides confirmed this afternoon that the Royal couple had left Buckingham Palace. A helicopter was seen to take off shortly after 1pm, before the Royal Standard was taken down from the palace.

The 90-year-old Queen and Duke, 95, were originally expected to travel on Wednesday and security arrangements were put in place at King's Cross and King's Lynn.

But shortly before they were due to board their train, palace officials said they had postponed the trip because of illness.

A Buckingham Palace spokesman said: 'The Queen and the Duke of Edinburgh have heavy colds, and so have decided not to travel to Sandringham today.'

This morning reporters at the station were told that the Royal couple were not expected to make the 100-minute journey by train between London and Lynn today.

Instead, they boarded a helicopter, which was seen taking off from the grounds of the palace at around 1.15pm. The Royal Standard, which is traditionally flown whilst the Queen is in residence was taken down shortly afterwards.

This afternoon, a spokesman added: 'I can confirm that the Queen and Duke of Edinburgh have left Buckingham Palace and are travelling to Sandringham.'

The Queen recorded her annual Christmas speech before falling ill, the palace has confirmed. It will be broadcast as normal, at 3pm on Christmas Day.

On Tuesday it was announced that the Queen would be stepping down as patron from 25 national organisations at the end of her 90th birthday year, with the patronages passing to other members of the Royal Family.

The move is likely to be seen as a common-sense decision which acknowledges the Queen's advancing years but Buckingham Palace stressed the monarch is still patron of around 600 organisations.

The Queen and Duke, 95, were surrounded by their family on Tuesday when they hosted their annual Christmas lunch for dozens of relatives at Buckingham Palace.

Despite their advancing years, the couple appear to remain in good health and have missed few official engagements in recent years due to illness.

Almost 30 members of the Royal Family are expected to spend Christmas in Norfolk, with most scheduled to arrive on Christmas Eve, when celebrations traditionally begin with high tea in Sandringham's ballroom.

In the evening, presents are opened before a candlelit supper.

Crowds of wellwishers traditionally gather outside the Church of St Mary Magdalene to greet the Royal Family after the Christmas Day service.

Prince William, the Duchesss of Cambridge and their young children Prince George and Princess Charlotte are expected to be absent this year, spending Christmas with the Duchesses parents Michael and Carole Middleton at their home at Buckleberry near Reading, Berks.

Prince Charles and Duchesss of Cornwall will be spending Christmas Eve and Christmas day at Sandringham, along with Prince Harry.

Also present will be the Duke of York and his daughters princesses Beatrice and Eugenie.

The Princess Royal and her husband Vice Admiral Sir Timothy Laurence will attend the gathering, along with Mike and Zara Tindall and their daughter Mia; and Peter and Autumn Phillips and their daughters Savannah and Isla.

Also present will be the Earl and Countess of Wessex, with their children James, Viscount Severn and Lady Louise.

Well-wishers will gather on Sunday when the Royals attend the Christmas Day service at the Church of St Mary Magdalene, near Sandringham House. Spectators queue from the early hourse to be sure of a good vantage point.

Family members walk to church, through the crowds, on their way to the service, with the Queen arriving by car.

After church Royal party then returns to Sandringham House to enjoy a dinner of Norfolk turkey and all the trimmings before watching the Queen's speech.

The Queen's grandfather King George V sat down at Sandringham for the monarch's first-ever Christmas message in 1932, addressing the Commonwealth via the radio.

Sitting in the same chair and at the same desk at Sandringham from which her father King George VI had made his final Christmas address, the Queen made her first speech in 1952.