Sales at Waitrose leapt 6% to £132.2m in the 22nd week of its current financial year versus the same week in 2014. 

Mark Williamson, commercial director, attributed the increase to “summer sunshine, British sporting heroics and US Independence Day parties”.

He said: “The growing number of myWaitrose customers signing up to the ‘Pick Your Own Offers’ scheme in a week featuring the sun drenched British Grand Prix, Wimbledon’s battling Brits and the inspirational Women’s England football team, helped deliver an encouraging performance.”

The 22 weeks to 4 July saw an overall increase of 0.9% on last year and were up 5.8% compared to the same period in 2013/2014. 

Champagne sales stayed strong, Pimm’s jumped 137%, rosé wine leapt by 43% and gin increased by 34%. Mixers were up 67% and record breaking beer sales saw bottled beer up 47%.

Good weather and 4 July falling on a weekend contributed to the strong sales, with Waitrose Aberdeen Angus mini beef burgers were up 136% and essential Waitrose sirloin steaks were up by 115% following strong promotional activity. Traditional barbecue fare also saw rises.

Williamson added: “Foods more traditionally associated with picnics are seemingly more popular than ever as we saw the biggest week ever for delicatessen outside of Christmas and a record week for our Food to Go range where sales were up by almost 18%.

"Quiche sales were up by 29%, dip sales by 13% and olives and antipasti sales were up by 18%.”