Following a boycott by hard-line Scottish nationalists, sales of Tunnock’s iconic tea cakes have risen by 10%.

Adverts for the Scottish snacks appeared on the London Underground at the beginning of this year featuring the words ‘Great British Tea Cake’.

This led extreme Scottish nationalists to stage a protest outside Tunnock’s Lanarkshire headquarters, where they called for a boycott of the tea cakes. This was a politically motivated attempt to force the country’s most famous confectionery company to crumble.

But it has emerged that the campaign backfired, after Tunnock’s revealed this week that sales were bolstered by the controversy. The company said the sales surge was fuelled directly by the publicity unwittingly created by the protesters.

Such is the interest in the brand that the firm has now released a range of tea cake-themed merchandise.

Fergus Loudon, operations director at Tunnock’s, said: “It meant the Tunnock’s name was being talked about all over the world and people are still talking about it.

“It prompted a lot of people to go out and buy tea cakes, and has been fantastic for us in terms of sales. There was a definite spike. …Sales are very, very strong. Our order book is full to overflowing.”

Last December, an online petition was launched, targeting the use of palm oil by Tunnock’s.