Supermarket shoppers bought more than 10 million packs of Christmas biscuits in October, latest Kantar Worldpanel data has shown.

The Christmas season has begun in earnest for UK retailers, according to the retail analyst, which last month reported supermarkets sold more than £5m worth of Christmas puds and mince pies in September.

“Consumers have already been digging deep in preparation for the holiday season, buying 10.1 million packs of traditional Christmas biscuits in October alone,” said Fraser McKevitt, retail and consumer insight head at Kantar Worldpanel, which this week published supermarket sales data for the 12 weeks ended 5 November.

“The British public is only just getting started when it comes to Christmas shopping, and is expected to shell out a whopping £28.7bn at the grocers in the final 12 weeks of 2017,” he added.

The Kantar Worldpanel showed total supermarket sales have grown 3.2% by value in the past 12 weeks. The growth has been driven by price increases, with volume sales up less than 1%.

Like-for-like grocery inflation is now 3.4%, its highest level since November 2013.

For the fifth consecutive period, the data showed Lidl was Britain’s fastest growing supermarket with sales up 15.1%, thanks primarily to new store openings. Sales at Aldi rose 13.1% (see table below).

In contrast to a general market focus on own-label lines, brands were the fastest-selling products at Sainsbury’s, which enjoyed an overall 2.6% hike in sales. This made it the fastest-growing among the big four supermarkets (Tesco, Asda, Sainsbury’s and Morrisons) for the first time since April 2016.

“Sainsbury’s strongest growth came from both its Local convenience stores and online sales,” said McKevitt.

Cheaper and more premium own-label lines delivered a strong performance at Asda, with its budget Farm Stores range up 88%, while sales of its Extra Special line were up 22%.