The John Lewis Partnership reported a 12.7 per cent decrease in department store sales in the week to August 9 compared to a year ago. Only two department stores, Nottingham and Edinburgh, saw growth.

Supply-chain director for department stores Patrick Lewis said: "As the temperature rose, footfall and sales dipped in direct proportion and we ended with one of the lightest Saturdays we have recorded in recent years."

The John Lewis figures are likely to prove a bellwether for the performance of other UK retailers during a heatwave which saw temperature records broken. The SPSL retail traffic index shows customer numbers down by 12.5 per cent in the week beginning August 3, and 17.8 per cent in London and the south east.