A murder trial jury has heard the emergency phone call a man made as he tried to stop a gang of masked teenagers from stealing his quad bike moments before a police officer was killed when he tried to intervene.
In the 15 minute call Mr Wallis tells the 999 operator he is going to confront them outside, despite seeing them armed with “weapons”.
The operator told him police were on their way and said: “Don’t go out there. You can’t go out there. If they’ve got a weapon you are going to get hurt.”
Henry Long, 18, admits the manslaughter of PC Harper but denies murder. Long and two boys aged 17 have admitted conspiracy to rob but his co-defendants deny manslaughter.
On Thursday, 12 March, Mr Wallis told the Old Bailey in London his brand new Honda TRX500 - which was worth £19,000 - was stolen from his home in Bradfield Southend in rural Berkshire around 11.15pm on 15 August last year by a group of men in balaclavas.
Mr Wallis said he saw the same masked men in a car which parked outside his property six hours earlier.
Prosecutor Brian Altman, QC, asked Mr Wallis what he said to them at that point.
“I said ‘Can I help you gentlemen?’,” said Mr Wallis, who said they replied dismissively and in an intimidatory tone, before leaving.
Mr Altman asked him if he rang the police at that point.
“No, I didn’t. I was contemplating it,” he replied.
Six hours later, after dark, the men returned and this time he did call the police because he knew “something was afoot”.
Mr Wallis said he got out of bed when he saw a car’s headlights.
The jury was then played the 999 call which ended when PC Harper and his colleague, PC Andrew Shaw, arrived despite being “well beyond the end of their shift.”
The trial has heard PC Harper suffered “absolutely catastrophic, unsurvivable injuries.”
Mr Altman said his uniform was “ripped and stripped from his body” and he was “swung from side to side like a pendulum” as the getaway car, a Seat Toledo, sped away from the scene of the crime.
When the gang’s getaway car - which had tape over his rear number plate - was found at a nearby traveller caravan site police found inside it an axe, a hammer, three crowbars and a pair of choppers.
Mr Altman said all the weapons were to be used “if anyone stood in their way.”
He said: “Constable Harper did try to stand in their way and paid the ultimate price for it.”
In English law murder is the causing of death with intent, while manslaughter is causing death unintentionally.
The trial continues.