In an investigation first published in January this year, GB News found examples of people being hit with the £5 surcharge, despite the sender having bought the stamps from reputable places, such as Post Office, stores with Post Office in them, and well-known retailers.

In March, we revealed Royal Mail had apologised for branding a genuine stamp as “counterfeit” and incorrectly charging the recipient £5 for the post.

Royal Mail’s Senior Public Affairs Manager Michael Hogg confirmed the stamp had been re-checked by the Revenue and Protection team and it was confirmed to be genuine.

In a letter, seen by GB News, he said: “Royal Mail had therefore been wrong to apply the surcharge and I am very sorry that our actions have failed you on this occasion.

“I wish to assure you this matter has not been taken lightly and whilst it is rare that items are incorrectly charged, an investigation is now underway by senior colleagues at Royal Mail Revenue and Protection to ascertain why this has happened, and what can be done to prevent it from happening again.”

Nick Landon, Chief Commercial Officer, said: “The combination of new barcoded stamps with added security features and Royal Mail actively working with retailers, online marketplaces and law enforcement authorities, has led to a 90 per cent reduction in counterfeit stamps.

“We want our customers to buy stamps with confidence and always recommend that customers only purchase stamps from Post Offices and other reputable High Street retailers, and not to buy stamps online – unless from the official Royal Mail shop.”

The new stamp scanner is in development and will be added to the Royal Mail app, which has already been downloaded on more than 14 million phones.

Customers will be able to scan stamp barcodes and check for themselves whether it is a recognised counterfeit stamp.

Royal Mail has also announced increased partnership working with retailers and online marketplaces to stop the sale of counterfeit stamps.

There will also be increased activity to raise public awareness about fake stamps, including revised guidance and advice to help customers protect themselves.

LATEST DEVELOPMENTS:

A Royal Mail spokesperson said: “Royal Mail takes the illegal production of counterfeit stamps seriously. Since the introduction of barcoded stamps we have been able to significantly reduce stamp fraud through added security features.

“Every barcode is unique which allows us to identify whether a stamp is genuine or not, and whether they have been previously used.

“We want our customers to buy stamps with confidence. We strongly recommend that customers only purchase stamps from Post Offices and other reputable High Street retailers, and not to buy stamps online – unless from the official Royal Mail shop.

“Our website provides customers with guidance on how to spot counterfeit or used stamps and we urge customers to report any suspicious stamps to Royal Mail via our website at Report a Stamp Fraud so that we can investigate.

“We are working hard to remove counterfeit stamps from circulation. We regularly monitor to detect suspicious activity, such as sales of heavily discounted stamps and work closely with retailers and law enforcement agencies to identify those who produce counterfeit stamps.

“We have a robust, multistage process in place when assessing whether stamps are genuine. This includes a thorough examination using specialist equipment, then a follow-up inspection by a skilled member of the team before any stamp is marked as counterfeit or pre-used.”