North Wales Police were forced to clarify the law on Monday, confirming that putting the sign up was not illegal, reports the Telegraph but official advice maintained that putting up such signed could breach the rights of shoplifters.

Asked if Sir Keir held the same view as Rob Davies, the owner of Run Ragged retro shop in Wrexham, the Prime Minister’s official spokesman said: “It is not the language I would directly use but we have been very clear through our actions we take shoplifting seriously, we understand the blight that shoplifting has on our high streets and local businesses.”

The comment comes after Alex Davies-Jones, the victims minister, admitted that shoplifting had “got out of hand”.

Mr Davies put a handwritten note in his store following repeated thefts that read: “Due to scumbags shoplifting, please ask for assistance to open cabinets.”

But following a complaint from a member of the public, police officers attended the 61-year-old’s retro shop and told him the sign could cause offence.

What is the official advice?

Advice from the Information Commissioner’s Office said putting up images of thieves in a local area, such as in shop windows, “may not be appropriate” behaviour.

Its advice page for shopkeepers on how to tackle shoplifting said retailers “must only share personal information that’s proportionate and necessary to achieve your purpose”.

Rhodri Ifans, the district inspector for Wrexham city, said: “Having searched our records, we have not been able to locate a report of an officer attending the store.

“It does not appear any offences have been committed, and it would be up to the shop owner to decide whether he displayed such a sign in his store.

“We will contact the owner to identify which officer it was who spoke to him, and to ensure that any incidents of retail crime at his store are reported to officers at the earliest opportunity, to enable us to effectively respond to any offences.”

‘Too little, too late’

Mr Davies told The Telegraph he had not yet been contacted by police, but that either way it was “too little, too late”.

He said: “I am not being funny but how much trust are we going to place in them now? I wasn’t expecting much from them anyway though.

“Them acknowledging it is good but they already admitted it wasn’t illegal when they told me it might be offensive, so it doesn’t really make any practical difference.”

How bad is shoplifting in the UK?

Shoplifting hit a record high of 530,643 offences reported to police in the year to March, a 20 per cent increase on the previous year’s total of 444,022.

In July, Yvette Cooper, the Home Secretary, announced plans for extra officers to be deployed on the streets of 500 towns in a summer blitz on shoplifting and anti-social behaviour by “thugs and thieves”.

Robert Jenrick, the shadow justice secretary, said: “Of course shoplifters are scumbags. I would use stronger terms than that.

“They are ruining livelihoods and destroying high streets across the country.

“The police need to go after each and every one of them because right now the odds of a shoplifter being caught are next to zero. Crime should never pay.”