Was it an innocent mistake...? Or a carefully calculated PR stunt, aimed at turning the heads of drivers on their way into King's Lynn.

At first glance, you might think someone had slipped up. But the banner on Benefer Way, advertising a purveyor of jacket potato, has been like it for a number of days.

Today Jamie Richardson, who runs the business with his partner Charlotte Kerr, admitted: 'It was totally deliberate. Instead of buying a new banner I thought we'd turn it round and it's had a great effect.

'We've had a lot of people coming up saying: 'Do you know your sign's upside-down..?'

While burger bars might have a slightly low-tech image, the couple have set up a website and have QR codes on their menus so customers can order online.

'We've brought it up to date a bit,' said Mr Richardson.