Bradford supermarket chiefs today admitted being completely baffled over how a packet of four-year-old cakes found their way on to a store shelf.

Shoppers Anthony and Diane Shaw said they were left "totally gobsmacked" after spotting the marshmallow treats - with a best before date of September 14, 1996 - among their weekly groceries from the Morrison's store in Laisterdyke.

The couple, from Palin Avenue, Bradford Moor, contacted the city-based supermarket chain who launched a full investigation.

But store chiefs admitted they were at a complete loss to explain how the offending Snowballs confectionery had slipped through their rigorous programme of checks.

They apologised for the problem.

Mrs Shaw, 43, said: "We had done our shopping the day before and I was packing a lunch for my daughter Stacey, who was going on a school trip.

"I put one in her lunch box and put another on the side for me to have with a cup of tea."

It was only when the 12-year-old Undercliffe Secondary School pupil set out on her walk to school that Mrs Shaw discovered the problem.

"I bit into it and it was really tough. At first I thought we must have bought another brand but then I realised something was wrong and looked at the box. When I saw the date on there I just couldn't believe it."

Mrs Shaw ran out of the house to catch Stacey en-route, removing the chocolate covered treat from her bag.

Forklift driver Anothony, 39, said: "My wife phoned me at work and my first reaction was 'have you got your glasses on?'"

"But when I saw the packet, I just couldn't believe it. You can expect goods to be a couple of days out of date or even a couple of weeks but this is just incredible."

The couple went back to the store and later to the firm's headquarters in search of an explanation.

Mr Shaw then contacted solicitor Jaroslaw Stachiw, of Bradford-based Stachiw and Bashir, who is pursuing an explanation and compensation payment.

He said the couple had been offered a "derisory amount" of £10 after the incident and added they were entitled to know how the incident occurred.

Mr Shaw, who still shops at the store, said: "This is not about money, I just want to know how this happened.

"No real harm was done in this case but if someone else ate food this far out of date, anything could happen." A spokesman for Morrisons said: "We were must concerned to hear about this highly unusual incident. We go to great lengths to ensure that stocks are maintained properly and have a strict code checking procedures in place. We are therefore at a loss to explain how this could have happened."

He said that all action had since been taken - including a double check of all the stock - to prevent a repeat of the incident.

And he added: "We are sorry that Mr Shaw is still unhappy with the outcome.