Alan Pemberton was accused of abusing his wife

Frank Mullane's sister Julia Pemberton was shot, along with her son William, by Alan Pemberton in Newbury in 2003.

Mr Mullane, of Swindon, will meet Home Office minister Baroness Scotland on Thursday to raise his concerns.

Thames Valley Police was criticised for its emergency response - nobody entered the house for nearly seven hours.

I've got about one minute before I die Julia Pemberton's 999 call

Mr Mullane's MP, Julia Drown, is to accompany him to the meeting with Baroness Scotland.

She said: "The family repeatedly and persistently called the police after there were threats to kill Julia and they begged the police to attend the house to pick up corroborating evidence.

"The police said they would attend but they never did and, as such, they didn't take action on what is a serious crime, threat to kill.

"There basically wasn't any domestic violence policy in place before July 2003, and the police weren't following Home Office guidelines to take a pro-active and serious approach to domestic violence."

Mr Mullane has now called for an inquiry into the deaths.

Police cordoned off the area but delayed entering the house

An inquest held in Reading last year, heard the "harrowing" transcript of a 16-minute 999 call to an emergency operator in which Mrs Pemberton described how her husband was rampaging through their house in Hermitage.

At one point she told the operator: "I've got about one minute before I die."

Shortly after murdering his wife and son, he turned the weapon on himself.

A Berkshire coroner recorded a verdict of unlawful killing on the deaths of Julia and 17-year-old William and put Mr Pemberton's death as suicide.

Peter Neyroud, Thames Valley Police's chief constable apologised for the delay, saying it "could not be justified".

A statement from him read: "Having reviewed the case in some depth, there are some aspects of it that the force would handle differently, but Thames Valley Police does not believe in any way that this would have led to us predicting or preventing Julia and William's murders."