Upmarket food retailer Fortnum & Mason posted a sales surge of 17.3% in December, the highest monthly level in the retailer’s 305-year history as online sales soared 45%.

The retailer’s flagship store in Piccadilly served 8% more customers year on year, with sales up 13.5%.

Online sales rocketed 45%. The retailer said its £3m investment in warehousing and delivery systems ensured customers received their Fortnum & Mason hampers in time for Christmas.

Fortnum & Mason chief executive Ewan Venters said: “We had a splendid Christmas, the best in our long history for sales but also in terms of the atmosphere in store, which is a huge tribute to the effort of all the team.

“Our online business is growing rapidly but the performance of the iconic store underlines its position as a destination.”

Fortnum & Mason said top sellers across the period were advent calendars, sales of which soared 113% year on year, Christmas tea towels, which were up 119% and Christmas biscuits, which rose 109%.

Fortnum & Mason said the strong Christmas performance built on their “bumper” sales around the Queen’s Diamond Jubilee last year. Venters added that the retailer was benefitting from a “halo effect” created by the Jubilee and the Olympics.

Venters said: “Our Christmas trading crowned a very successful year for Fortnum’s and we expect to build on that throughout 2013.”