Waitrose’s total divisional sales – excluding fuel – were down by 0.2% last week (to September 24), compared with the same week last year.

The supermarket chain said blamed ‘tough comparatives’ as a result of the later fall of its Half Price Event during 2015.

This year’s Half Price Event concluded on Tuesday September 20 but ran for a full seven days during the equivalent trading week last week.

Waitrose personnel director Helen Hyde added: “Thanks to last week’s balmy weather, traditional summer staples such as ice and soft fruit were up 34% and 10% respectively.

“Sales of halloumi, a popular cheese for the barbecue, rose by 32%, while avocado sales also increased by 32%.”

She added: “Shoppers were inspired to bring the sunshine indoors as flower sales were up by 20%, led by sunflowers and gladioli.”

Sales of traditional summer staples such as soft fruit were up at Waitrose last week