An investigation has been launched at a West Midland Marks & Spencer after shoppers let themselves in through a main door that had been left unlocked.

The Wolverhampton store was closed on Saturday but Boxing Day bargain hunters found one of the front doors was open and wandered in.

Police arrived at the Dudley Street branch after the alarms were triggered at 1pm.

Banker Stephen Gleeson, aged 26, was hitting the sales when he tried to get into the shop. “I thought it was open because I could see a bit of activity inside,” said Mr Gleeson, of Coalpool, Walsall.

“But when I got to the door the police were there stopping people from coming in. The doors had been left open and people had got in and started shopping until they were told to leave immediately.”

Wolverhampton office worker Ian Cartwright made it through the front doors of M&S with his parents.

The 41-year-old said: “We went shopping on Boxing Day and sauntered straight in.

“Only one door was open but we thought it was a restriction due to the start of the sales.

“We took around five paces in but didn’t even make it up the first set of steps.

“Somebody told us there was no staff on duty.

“I couldn’t see any evidence of stuff being stolen. It was fairly busy and none of the escalators were working.”

Store bosses said an investigation had been launched.

A spokesman said: “We take security matters extremely seriously and are conducting an investigation into how customers were able to gain access to the store. The store’s alarm system alerted security staff and police, who were quickly on the scene.”

The M&S sale started yesterday.