Christian Hobbin, 42, of Stamford Bridge, died on January 25 when he drove his car at top speed into Carmire Gate, a stone archway at the entrance of the stately home.

Traffic Constable Stephen Kirkbright told the coroner that he had later discovered the site of the tragedy on a suicide website.

TC Kirkbright also said that his investigation team estimated Mr Hobbin to be driving his silver BMW at a minimum speed of 83mph when he struck the stone gate.

He said: "To the best of my knowledge, considering the extensive damage to the car, there was nothing apparent that would have caused the driver to lose control.

He said the narrow width of the arch meant he would expect someone to slow down well below the 60mph speed limit on the road.

Eyewitness Steve Wooley told the inquest: "The road on which I was driving was very familiar to me, and there was just one other car on it at the time driving towards me.

"The car was travelling at some speed and even though it was my right of way through the gate I held back," he added.

"The car increased its speed somewhat and, at the last moment, it veered to the right and collided with the wall. I saw no reason why the car should have done that.

"I got out my vehicle and went round to see if there was anything I could do. There was nothing I could have done."

Mr Hobbin, a train driver, left a suicide note for his wife Deborah Hobbin at the home they shared in Roman Avenue North, Stamford Bridge. The couple had been married eight years but had decided to separate just weeks before Mr Hobbin's death.

His widow told the coroner how her husband had "threatened to take his own life several times before over a number of years" including the past few months.

Coroner Michael Oakley recoded a verdict that Mr Hobbin killed himself."

Since Mr Hobbin's death, which was the third in three years, wooden bollards have been placed in front of the stone archway in a bid to prevent further incidents.