UK grocery sales rose by 14.3% during the 12 weeks to May 17, the fastest rate since comparable records began in 1994, as Britons adapted to the national lockdown, data from market researcher Kantar showed today. 

The period included both the pre-lockdown rush to the shops in March, and eight weeks of stay-at-home advice from the government. 

The UK has been in lockdown since March 23 though restrictions are being gradually eased. 

Of Britain's big four grocers, industry leader Tesco was the best performer with sales up 12.7%, closely followed by the second biggest player Sainsbury's with a 12.5% increase. 

The UK's fourth biggest supermarket group Morrisons' saw sales rise by 9.8%, while Walmart owned Asda was the laggard with a 6.5% increase. 

The overall star performer was the Co-operative, the sixth biggest grocer in the UK, with a sales increase of 30.8%. 

Kantar said that in the most recent four week period to May 17 grocery sales growth accelerated to 17.2% year-on-year as the government announced the first stage of easing lockdown restrictions. 

In the most recent four weeks, the trend towards fewer, larger shops evident in April continued. 

Kantar said shoppers visited a supermarket three and a half times per week on average, meaning 100 million fewer trips overall than the same month last year.

But they increased their spend each trip to £27.41-  nearly 50% more than they spent during pre-crisis times.