Part-time actor John is a real Tesco Extra

As well as serving up fresh fish, he works as a TV and film extra and has made more than 2,000 appearances over 14 years in 200 shows.

Whether it be playing a bandaged patient in Casualty, a crime officer in Midsomer Murders or a rioter in The Bill, John says he has played more characters than he can remember.

Most of the time, he is simply a face in the crowd or background, dressed up and asked to play out the role of a drinker in a pub in teen soap Hollyoaks, a Victorian man at the races in The Invisible Woman or an office worker in CBBCs Bert and Dickie.

But as well as being a backgrounder, he is also picked to play characters or act as a double for another actor. He played Thomas Dent, a murderer in the ITV show the Killers, Great Train

Robber Jimmy White in ITV drama Mrs Biggs and Professor Lennox in CBBCs Wizards vs Aliens.

He has also acted at Ewen Bremner's double on a number of shows, including in Great Expectations, where he stops a fight between two other characters, played by Robbie Coltrane and Tamzin Outhwaite.

A world away from his job behind the counters at Tesco Extra at Burnt Tree in Dudley, Mr Walker will pick up between £80 and £280 a day for his screen roles.

This has not only lined his pockets, but it has also seen him net romance – meeting his fianceé Neilum Raqia, aged 36, on the set of day-time show Doctors nearly five years ago.

"My role was to say to my wife, 'Joanne, she is here talking to Victor'", he said. "While saying it I looked off camera and saw the most beautiful woman I'd ever seen. I said the line a number of times and kept looking at her – straight away off screen we hit it off instantly."

The couple, who live in Holly Road, Dudley, and are set to marry this November, now combine their work as extras on television, and have appeared together on Misfits, Gavin and Stacey and Casualty.

The acting work all started for John when he spotted an advert to become an extra for a Doctor Who spin-off show for video called Auton 2 in 1998.

An avid fan of the sci-fi series, John, who then lived in Bath and worked in the head office at Safeway, signed up for the role alongside Nick Briggs, who is the voice of the daleks today, in Dorset. John enjoyed the work so much he signed up to an acting agency in Bristol, putting himself forward for dozens of roles.

Despite working 9am to 5pm for Safeway, the supermarket firm allowed John to organise his work around his acting.

At his peak in 2005, he was acting as an extra on television sets once a week.

He said: "I was working as everything on everything, and loving it at the same time.

"You are not supposed to appear on rival soaps, but I did it – I was the doctor on Coronation Street, Emmerdale and Hollyoaks all in the same week.

"The roles I was picked to do were always fun, and I find myself very often picked to be a doctor or policeman.

"It's a great chance to get away from real life, have some fun and see some of the stars.

"Most were great, some not so, but I wouldn't want to name names."

But it is not just random extra roles John and fianceé Neilum get called up for. The couple have regular show characters – best known as a policing pair on Midsomer Murders, Scott and Bailey and DCI Banks.

John said: "People often say "I saw you on TV last night" – I think I've done so much I'm on ITV3 every day.

"It was great first seeing yourself on the screen, but now we're both used to it."

In 2008, John took redundancy to pursue a career in acting and production, but soon found the new career path did not suit him and returned to part-time work.

Asked what makes him a successful extra, John said: "Blending in the background, not making big movements and having the ability to mime rubbish with no-one knowing.