Supermarkets enjoyed a surge in sales as the tiering systems and new national lockdowns helped boost sales by 12.2% in the 12 weeks to January 24, according to the latest Kantar grocer data.

Analysts said this was an acceleration on the Christmas period, as the reintroduction of national lockdown restrictions and the closure of cafes, restaurants and pubs saw eating out of the home curtailed once more.

Kantar added that in January shoppers spent £1 billion more on supermarket food and drinks compared with the same month a year ago.

Fraser McKevitt, head of retail and consumer insight at Kantar, said: “As well as the usual healthy new year’s resolutions, shoppers also looked to treat themselves in January as a way of coping with another month of restrictions.”

He pointed out that vegan ranges were particularly popular, with 6.6 million households buying vegan-specific products – up 10% on a year ago.

During January, there was a 23% boost in vegan products, with families adopting Veganuary, he added.

Another new year movement – Dry January – also saw low and no-alcohol beer grow 12%, although this was far outweighed by alcohol sales, which grew 29% during the 12-week period to £234 million.

Mr McKevitt added: “This period also captured a unique New Year’s Eve – with many people celebrating the night at home instead of going out or hosting family and friends.

“Delivery companies such as Just Eat and Deliveroo felt the benefit as more people than usual tucked into a takeaway, and such services accounted for 6% of all online shopping trips on December 31.”

Iceland enjoyed the strongest growth of all the supermarkets with physical stores – with sales rising 21.8% in the 12-week period compared with a year earlier.

It was followed by Morrisons up 14.3%, Tesco up 12.2%, Lidl up 12.1% and Sainsbury’s up 12%.

Despite the strong growth and boost in sales from remaining an “essential” retailer, as restaurants, pubs and cafes remain closed, Iceland has decided to keep its business rates holiday payments.

Morrisons, Tesco, Lidl and Sainsbury’s all agreed to repay their rates bills during the period.

Online-only supermarket Ocado was the strongest overall with sales up 36.6% compared with a year ago.

The slowest growth came from Aldi, which managed a sales boost of just 5.7%, followed by Asda at 9.9%, Waitrose at 11.3% and Co-op up 11.4%.

One year on since the first Covid-19 cases were detected Kantar said it has seen clear shopping patterns splitting down generational lines.

In the four weeks to January 24, people under 28, who are typically more open to visiting physical shops, increased spending in larger physical stores by 12%.

However, over-45s cut back spend in bigger supermarkets by 1%, turning to online shopping instead.

Online shopping hit a record market share of 14% in January, led by the oldest demographics.

Mr McKevitt explained: “Retired households have boosted their online spend by a staggering 229% compared with January 2020.

“Older people are clearly getting more comfortable and proficient at ordering online and they now make up 28% of the 6.4 million who used online services in Great Britain this month.”

The data also shows parents are spending an extra £50 a month on groceries in the month of January than they did last year, to provide lunches for children unable to go to schools closed during the current English national lockdown.

Products including pasta were up 22%, chocolate spread up 42% and peanut butter up 39%.

The high growth is expected to slow as the vaccine rollout takes hold and the hospitality sector eventually reopens, whilst the end of the Brexit transition period has not seen any significant price rises currently.