LONDON (Reuters) – The marriage of Prince William to Kate Middleton next year could give a £620 million ($985 million) boost to the British economy, retail reseachers Verdict said yesterday.

The forecast came as Asda, Britain's second-biggest supermarket group, said it was already selling a £5 mug to commemorate the engagement of the heir to the British throne to his long-term girlfriend, announced on Tuesday.

Verdict estimated the engagement could be worth £12-18 million in merchandise sales, while sales of wedding-related products could top £26 million.

The real boost to the economy, however, could come from creating a "feel-good factor" among consumers that proved elusive this year with the England team's dismal performance in the football World Cup.

Verdict forecast food and grocery retailers could benefit to the tune of £360 million as shoppers buy treats like wine and champagne to toast the happy couple, while travel and tourism revenues could be boosted by £216 million.