“He could have been lying there an hour, an hour and a half. He was cold and very pale.

“I got a cushion and put it under his head. I dialled 999 and said my partner has had an accident.

“The ambulance and police was here within seven minutes and a police officer, a woman said he was dead.

“A Police officer said death was instant. The police treated it as a crime.”

It was an absolutely freak accident. There had not been a row – I had not hit him

Teresa Marshall de Paoli

She contacted his daughter Lady Kathryn Brudenell Bruce who dashed to the scene after the tragedy late Sunday evening.

“I had to spend all night in an arm chair drawing room with Lady Kathryn. We could not go into any other room.

“The police were there all night and all the following day.”

The pair had lived at the house for 16 years since they left their cottage on the family’s 4,500-acre estate in the Savernake Forest near Swindon, Wilts.

The thrice divorced Marquess, whose granddaughter Bo Bruce appeared on BBC song contest The Voice, went to Eton before serving as a captain in the Royal Horse Guards, and later became a stockbroker.

A spokesman for the Met Police said: “Police were called by the London Ambulance Service at 20:05hrs on Sunday, 12 May, to an address in Abdale Road, W12, after a man in his 90’s was found deceased.

“Officers and London Ambulance Service attended.

“His next of kin have been informed.

“The death is as unexpected but not being treated suspicious.”