Royal wedding bells could set retailers’ tills ringing to the tune of almost £400m.

Sales of wedding-related merchandise following the engagement of Prince William and Kate Middleton could amount to about £44m, according to estimates by retail research house Verdict.

And grocers may generate additional sales of £360m as customers buy treats such as champagne to celebrate the occasion, Verdict said.

Verdict consulting director Neil Saunders said it was difficult to forecast the precise impact. He said: “The scale largely depends on how it will be executed. If, as expected, it is a big set-piece event it could well capture the nation’s imagination and provide a fillip to the retail sector.”

Asda became the first big retailer to market with Kate and Wills merchandise when it put a commemorative mug (pictured) on sale for £5 the day after the engagement was announced.

An Asda spokeswoman believed the wedding could prompt “hysteria similar to than when Charles and Di wed” and said: “Royal crockery is a good British tradition. Nothing says congratulations like your face on a mug.”