How Cameron's father-in-law strong-armed me off his land

Sir Reginald Sheffield, the father of Mr Cameron's wife Samantha, is said to have 'screamed and shouted' during a heated confrontation with a neighbour.

John Kilmartin, whose semi-detached former council house is next to Sir Reginald's Normanby estate in Lincolnshire, claimed he was assaulted when he went to complain to the baronet about one of his tenant farmers.

He said: "Sir Reginald is a big bully multi-millionaire landlord who is trying to push me around.

"He's a pompous, arrogant pig. Before all of this I thought he was a pillar of the community."

The scuffle is said to have taken place over an 18ft by 2ft plot of land which father-of-two Mr Kilmartin and Sir Reginald's tenant Simon Ogg both claim they own.

Mr Kilmartin said he had gone to see the baronet at the end of April to try to resolve the matter.

His account of what followed will undoubtedly make uncomfortable reading for Tory leader Mr Cameron, who is highly sensitive to all reminders of his privileged background.

His wife Samantha, 36, is the eldest daughter of Sir Reginald, 61, and his first wife Annabel Jones.

Her parents' five-year marriage ended in 1975 and 58-year-old Annabel is now married to another aristocrat, Tory grandee Viscount Astor.

Mr Kilmartin said that when he went to see Sir Reginald, the baronet 'degraded' him by refusing to talk about the land dispute.

"He went back into his office and that was it," he added. "He just didn't want to know and didn't want to speak to me about it.

"I explained what had happened to his secretary. The next thing I know he comes back out, apparently aggrieved that I was still talking to his employee, and grabs hold of me.

"He then threw me into the hallway and slammed the door in my face, shouting, screaming and ranting at me.

"I went back to the car and rang the police immediately to report him for assault.

"I went to the station and gave a witness statement.

"I've since been told by police that they interviewed Sir Reginald under caution with a solicitor present but as I understand it no further action will be taken."

He added: "I respected him as a landowner but now, after the way he treated me and made me feel, I have no respect for him whatsoever.

"It's all down to how much land they own and they will take everything if they think they can.

"I was amazed at the way he treated me. I was merely trying to make my point as a private householder over a dispute with one of his tenants - which is far from over.

"I had my blood pressure taken the next day and it was through the roof. It has all been very distressing for me.

"I could have been hurt or worse by the incident."

Mr Kilmartin claimed that the disputed land was rightfully his because Mr Ogg's predecessor had put up a fence marking out the boundary.

But Mr Ogg last night said the row had since been resolved in his favour.

Humberside Police confirmed they investigated an allegation of assault involving Sir Reginald but said they had made no arrests and would not be taking any further action over the incident.

A spokesman said officers talked to witnesses and 'concluded that no offences had been committed'.

"After consultation with the Crown Prosecution Service it was decided that no further action was necessary and no arrests were made," the spokesman added.

Sir Reginald - a direct descendant of Charles II - remained tight-lipped last night, although his wife Victoria admitted the police had been called.