A combination of Diamond Jubilee fever and the wet weather buoyed sales at department store chain John Lewis last week, figures have revealed.

The retailer posted an increase of 18.1 per cent on the same week in 2011, helped by two bank holidays, half-term and promotions of Jubilee and Olympics-themed products.

Electricals and home technology purchases showed the biggest increase, with television sales up 65 per cent as households prepare for a summer of sport.

The best performing John Lewis store was Swindon, which saw its sales soar by 51 per cent.

Maggie Porteous, head of selling operations, new format, John Lewis said: “A number of key themes last week came together to give a boost to our trade.

"The Jubilee effect was, of course, at the top of this list, bringing with it a different fall of half term which meant that not only were there two bank holidays, but that many children and their families had the rest of the week off.

"That – coupled with the rain, some strong assortment promotions and the imminency of both Father's Day and the London 2012 Olympic and Paralympic Games – gave the division a resounding increase of +18.1 per cent on last year.

City analysts said the latest figures were impressive but unlikely to reflect the rest of the retail sector or prospects going forward.

Howard Archer, chief UK and European economist at IHS Global Insight, said: "It appears that consumers need a boost such as a major event or extended good weather to significantly step up their spending.

"Although consumer confidence improved in May, it is still extremely low compared to long-term norms."

Waitrose, the supermarket division of the John Lewis Partnership, saw a more sluggish 2.3 per cent rise in sales compared to last year.

Online sales grew, with Johnlewis.com achieving a 47.2 per cent increase while Waitrose was up 14 per cent.