Millions of pounds worth of "museum quality" art has been stolen from the home of a reclusive property tycoon.
Mr Hyams was not in the manor when thieves broke in
Thieves raided Ramsbury Manor - a 17th Century mansion in Wiltshire said to be worth more than £20m, and home of Harry Hyams - on Wednesday night.
A Wiltshire Police spokesman said the items taken, including fine art and porcelain, were "worth a substantial amount - into the millions".
The stolen items included a 1675 clock from the reign of Charles II.
Detectives believe it was a well-planned operation by professional thieves.
The police spokesman added: "We are investigating a high-value burglary. Items of substantial value have been taken. No-one was hurt in the break-in.
"It is one of the biggest burglaries round here for years."
Mr Hyams, who is in his late 70s and rarely seen in public, bought Ramsbury Manor in 1964 for a record price for a private house sale.
He was ranked the 155th richest person in Britain in the Times Rich List for 2005, with an estimated fortune of £320m.
A spokesperson for Mr Hyams said: "Everything that has been taken is readily identifiable, is of museum quality, and will be extremely difficult to dispose of.
"The building was occupied but Mr Hyams was not present at the time."