PRINCE Charles and his wife Camilla sat through a "hairy" mid-air drama when an in-flight emergency forced them to land minutes after take-off.
Fifteen minutes out of central London, a technical fault forced the royal helicopter to divert urgently to a nearby aerodrome.
Charles and Camilla were flying to Wales for a day-long tour to Hay and its popular annual festival of literature.
But minutes after boarding their flight, they were urgently diverted to Denham Aerodrome in Buckinghamshire.
The helicopter, which is believed to have been carrying up to seven people, developed a "technical fault" just minutes after take-off.
"The pilot carried out a controlled emergency landing after diverting to the airport," a spokesman for the royal couple said.
"It was quite a hairy experience," a source close to the palace added.
Despite the unscheduled stop the royal couple transferred to cars and continued on to the market town of Hay-on-Wye by road.
The couple finally arrived almost three hours late but emerged looking relaxed and smiling to be greeted by a crowd of several hundred well-wishers. Neither Charles nor Camilla alluded to their in-flight drama
An official investigation into the cause of the technical fault is now underway.
The lateness of the royal couple's eventual arrival meant that a planned leisurely tour of Hay had to be carried out more quickly.
The tour continued with visits to its open-air food market, Hay Castle and Richard Booth's Bookshop.
Well-wishers thronged the streets and cheered enthusiastically as the royal couple made their way round, often in teeming rain.
They then continued on by car to the nearby site of the Hay Festival of Literature, which began its annual 10-day run yesterday.
On the agenda was a visit to the festival's sprawling main bookshop, which played host to the launch of a Reading Agency campaign.
The independent charity has linked up with the annual festival to feature a special summer reading challenge.
Both Charles and Camilla attended the high-profile launch, which included hundreds of primary-school children.
A handful of best-selling children's authors, from Cressida Cowell and Korky Paul to Lauren Child, were also on hand.
The campaign aims to reach 750,000 4-11-year-olds and inspire them to read six books during the course of the long summer break.
The theme of this year's challenge is 'Creepy House' and the launch event included a range of themed activities and displays.
The summer reading challenge is the UK's biggest promotion of children's reading and is run by the Reading Agency with public libraries.
"We're delighted to be working with Hay to devise new ways to bring people powerful new reading opportunities and highlight the vital role of libraries in every community," said Reading Agency director Peter Florence.
After the festival visit, the royal couple parted and the Prince of Wales went on alone to Cardiff to attend the Welsh National Opera's opening new production of Wagner's 'Lohengrin'.