Pippa Middleton, sister of Britain's Duchess of Cambridge and possibly the country's most eligible single woman, is engaged to marry a hedge fund millionaire, the Daily Mail reported on Tuesday.

Boyfriend James Matthews went down on one knee to propose to Pippa, 32, on a walk last weekend in the picturesque Lake District in northwest England. Pippa said 'Yes', the newspaper's royal correspondent reported citing sources close to the couple.

Pippa turned heads when sister Kate married Prince William in 2011, wearing a figure-hugging Alexander McQueen dress that earned her the nickname 'her royal hotness' and launched her onto the society pages of Britain's celebrity-obsessed tabloid press.

Pippa began dating the 40-year-old Matthews nearly a year ago. The couple were recently spotted together at the Wimbledon tennis tournament.

No date has yet been set for a wedding that would expand Britain's extended royal family to include a couple with humble origins - both are grandchildren of coal miners from the north of England, the Daily Mail reported.

Kensington Palace did not immediately respond to requests for comment on the report. – Reuters