Ian Campbell has clocked up 5,700 hours walking the beat for the police over the past 19 years — but has not cost the taxpayer a single penny.

The father-of-two has been praised by Thames Valley Police for his dedicated service as a volunteer special constable, which the force believes has saved it £121,000 over the past two decades.

During the week, Mr Campbell, 49, is an IT manager at a high street bank but at weekends he joins regular officers out on the beat.

He said: “I get the best of both worlds.

“I love my day job but at the same time it is nice to get out there and deal with the public and deal hands-on with people's problems and reassure the public.

“The most important thing is you get to test yourself every day and experience aspects of life you perhaps wouldn't have done otherwise.

“One day I may be at a car crash, then dealing with a street incident or trying to resolve domestic violence.

“I've seen a number of things in the past 19 years and it certainly is an eye-opener.”

Mr Campbell is the longest serving Special Constable in the Vale of White Horse and has the second longest service history of any special in Oxfordshire.

He is now in charge of all Special Constables in the Vale, and he said he had no plans to give up his weekend role soon.

Special Constables have the same powers as the regular officers they work alongside, but volunteer in their spare time and do not get paid a wage.

Over the past two decades, Mr Campbell has been involved in some of the major crimes and investigations in the county.

These include investigating the unsolved murder of 30-year-old Vikki Thompson, who was killed while walking her dog in Ascott-under-Wychwood in 1995; the crash of a Harrier aeroplane near Tackley in 2006 and last summer's floods in Abingdon.

He has worked six years at Didcot and 11 in Abingdon.

He said: “I joined for the same reason as everyone else — to put something back into the community.

“It's easy to sit there and criticise but it's a lot more difficult to get up and do something about it.

“At this moment in time I have no idea when I'll stop. I shall carry on until I'm not efficient any more or not good value.

“I've seen many changes in the past 19 years and hopefully I'll see some more.”

Police spokesman Andrew Heath said the work carried out by Mr Campbell had saved the force an estimated £121,000, which would otherwise have been spent on training, equipment and wages. The long service award was handed out at a ceremony at Drayton Park golf club on Thursday.

Pc Patricia Caseman, of the fixed penalty support unit in Banbury, and Pc John Ottaway, of the protection group at Minster Lovell, were also given awards for 25 years service.