The Government’s top intelligence adviser has been unconscious in hospital for four days after collapsing at his home.

The Metropolitan Police have been investigating the mysterious illness that struck Alex Allan, chairman of the Cabinet Office Joint Intelligence Committee. They have, however, ruled out foul play. Reports that he may have been deliberately poisoned were dismissed by authoritative Whitehall sources last night.

As a precaution, toxicology tests were carried out to discover whether there was anything in his blood or urine that might explain his sudden collapse.

Scotland Yard initially became involved because two officers happened to be at the hospital in West London to which Mr Allan was taken on Monday. They recognised his name and started making inquiries.

Mr Allan, 56, whose wife, Katie Clemson, died of cancer last year, had told colleagues late last week that he was feeling unwell.

The police discovered, however, that he was well enough to visit his favourite website on the Grateful Dead rock group as recently as Saturday. One colleague said: “He is a very charismatic person and there were no indications that anything was wrong apart from him saying that he was not feeling quite up to scratch.”

Mr Allan, who has been chairman of the Joint Intelligence Committee for a year, does not have an intelligence background. He served as Permanent Secretary at the Department for Constitutional Affairs from 2004 until it merged with the National Offender Management Service last year to create the Ministry of Justice.

Colleagues said that Mr Allan was in a very serious condition last night.

Explore UK News

• Crime News

• Education News

• Health News

• Scotland News

Times Recommends

• Charles blazes trail as sun king
• Thalidomiders win payout 50 years on
• Libel gag on talk of 'medical hurricane'