Peter Williams, 67, was killed when PC Sean Schofield's marked Volvo T5 hit his car head-on at 94mph.

The advanced police driver hit speeds of 104mph moments before he ploughed into Mr Williams' VW Touran in November 2006.

Mr Williams, from Boltton-le-Sands, died in the Lancaster Royal Infirmary the day after the incident. His wife and passenger, Jean, broke both wrists.

Yesterday ((TUES)), Schofield, 38, was found guilty of careless driving, fined £500 and banned from driving for two years. He was acquitted of causing death by dangerous driving.

His co-defendant Andrew Massingham, 41, who was driving the lead vehicle in the police convoy, was acquitted of causing death by dangerous driving and did not face the alternative charge of careless driving.

As the seven men and five women of the jury gave its verdict, they sent a note to the judge accusing the police of "institutionalised complacency" for allowing such a training exercise to take place on the 60mph country lane near Carnforth.

Today, Mr Williams' son called on the police to "improve their driving practices".

Father-of-two Rev Geoff Williams, of Penwortham, near Preston, said: "The hardest thing for us has been the fact the accident was caused by traffic policemen, one of whom trains other traffic officers.

"They are usually the people who deal with accidents like this.

"We recognise police driving training on public roads is to some extent necessary and never entirely risk free.

"However, we would hope the impact on all our lives would lead both the individual officers and Lancashire Constabulary improve their driving practices."

During the three-week trial, Liverpool Crown Court had heard how Schofield was testing an electronic system for measuring vehicle speed that involved him chasing a car driven by trainer Massingham to register its speed.

During a 13-month investigation by the Independent Police Complaints Commission (IPCC) that followed, Massingham, from Heysham, was banned from driving after being snapped speeding on a road in Yorkshire.

Mr Williams said: "That did anger us. We thought had he not learnt any lessons from what happened?"

"But more than this we just wanted to know what happened. The issue of punishment is secondary.

"We would take no pleasure from seeing two policemen sent to prison – that is the last place they would want to be."

IPCC commissioner Mike Franklin said: "I have noted the verdicts and I will be seeking urgent discussions with Lancashire Constabulary about the findings of our investigation and whether there will be any disciplinary matters relating to the two officers.

"The key step also is for discussions to take place nationally to determine the appropriateness of this kind of police training.

"This investigation was conducted thoroughly, rigorously and with great sensitivity."

Lancashire Constabulary's assistant chief constable, Chris Weigh, said: "We will continue to work closely with the IPCC on what sanctions, if any, need to be taken and we will take forward the lessons learned from the investigation.

"This incident can only be described as a tragedy and one of the main things to come out of the IPCC investigation, as well as our own investigations, is how we can try to prevent anything like this happening again.

"Following the collision in 2006, the decision was taken to suspend Vascar training in order to see what lessons could be learnt from the incident.

"This type of training is still suspended and will not be introduced until a new training module has been developed that incorporates everything that we have learnt.

"Lancashire Constabulary will continue to review all of its training policies to ensure that they are in line with national guidance and that the strictest control measures are in place in order to minimise any risk to officers and members of the public.

"I hope Mr Williams' family will feel that a degree of justice has been served and we will look to support them in any way we can."

He said the two men would remain on "alternative duties" while the force "digested" what the court and the Independent Police Complaints Commission (IPCC) had said.