LONDON (BLOOMBERG) - When Prince Harry and Meghan Markle announced their engagement on Monday, Britain's souvenir firms sped into action.

Within hours of the news, websites went live selling limited-edition commemorative porcelain plates featuring the couple's official engagement portrait.

One analyst expects next year's wedding will amount to £60 million (S$109 million) in additional sales.

Kensington Palace has said the wedding will be in May but the exact date has not been announced.

The marriage of Prince Harry's older brother, Prince William, to Kate Middleton in April 2011 boosted the number of visitors to the country by 350,000 that month alone, according to the UK Office of National Statistics.

That wedding accounted for a £527 million increase in British retail spending, including £199 million on wedding souvenirs and memorabilia on the public holiday, according to an estimate from the Centre for Retail Research.

The centre's director, Mr Joshua Bamford, said the economic bump will likely be less pronounced this time. Unlike his older brother, Prince Harry is not the king in waiting. He is fifth in line to the throne and will be sixth after Middleton, now the Duchess of Cambridge, has her third child.

Mr Bamford imagines there will still be £60 million of shoppers' cash up for grabs.

On an annual basis, the royal family provides a £550 million uplift through tourism, estimates Brand Finance, a business valuation consultancy, with lines snaking outside Buckingham Palace, Windsor Castle and other current and former royal residences.

In all, 4.4 million people visited royal sites across Britain last year, according to Historic Royal Palaces, the charity that manages them.