Sophie Hardy Wilson, owner of Security Research, which was sold to Cray Electronics in October 1987, told the Independent she was commissioned to carry out the three-hour sweep for about pounds 600. She said: 'I was a bit surprised that they couldn't do it but they didn't have the kit. Apparently, their budget wouldn't run to the pounds 4,500 it would have cost to buy their own.'
Home Office officials were said to be astonished by another report, in the Sunday Times, that last year the Prince of Wales hired a private security company to electronically sweep Kensington Palace. It would seem private security has been included in royal protection for some years: the Independent has the name of a retired army officer believed to have undertaken security work.
And Squadron Leader Sir David Checketts, an extra Equerry to the Prince of Wales since 1979, is a former director of Electronic Systems International, which undertook electronic counter-surveillance operations, although Sir David said yesterday that he did no work for the Royal Family.
Mrs Hardy Wilson said she was asked to carry out the Ascot sweep by Superintendent Ted Molyneux, who was responsible for royal protection at the course.
Security Research is thought to have been recommended by bomb disposal officers at Chatham Barracks because it had developed a device called Broom, which detected the circuitry of bombs or bugs. 'We went on to supply Broom to the Ministry of Defence and we had already sold it to the French and Belgian police, but Mr Molyneux said Thames Valley's budget wouldn't run to it. But it only cost about pounds 4,500,' she said.
Superintendent Tom Wright, of Thames Valley police, was unable to comment on 1987 security, but said the force now had the equipment and men needed to carry out protection duties. He added that Thames Valley, which covers Dorneywood, the Chancellor's country residence, and Chequers, the Prime Minister's, recently had its protection complement increased by 55 officers.
Scotland Yard never comments on the security work of its Royal and Diplomatic Protection Department but one officer said it was responsible only for 'close protection' at events like Ascot.
The People and the Sunday Mirror ran full transcripts yesterday of a taped conversation allegedly between the Prince of Wales and his friend, Camilla Parker Bowles. Lord McGregor of Durris, the Press Complaints Commission chairman, said no complaint had been received.
Asked whether the tapes should have been published, he said: 'It is a very difficult question but if they were not, we would be in the strange situation where, like in 1937, the rest of the world knew something of primary interest to the British, that the British did not know.'
The Mail on Sunday quoted security service sources as saying there was a six-person unit at GCHQ with the sole task of monitoring royal telephone calls. Home Affairs Select Committee members are likely to raise the claims at lunch today with Stella Rimington, the head of MI5.
But yesterday Kenneth Clarke, the Home Secretary, insisted there was 'nothing to investigate,' adding there would be no inquiry into the 1989 taping of telephone conversations by members of the Royal Family.
He said: 'The security services are strictly controlled in their telephone tapping and I know of absolutely no evidence whatever to support even the wildest allegation that . . . (they) were involved.
'I am absolutely certain that the allegation that this is anything to do with the security services or GCHQ is just extremely silly and is being put out by newspapers who, I think, feel rather guilty that they are using plainly tapped telephone calls.'