Marks & Spencer has become Britain’s fastest-growing supermarket in a sign of the continued strength of its turnaround under chief executive Stuart Machin.

Figures from Kantar, seen by The Telegraph, show M&S’s sales rose by 12.4pc in September, outpacing the rest of the industry.

Waitrose, which is viewed as M&S’s closest rival, grew by 1.9pc over the same period, while M&S also outpaced major players including Lidl, Aldi, Tesco and Sainsbury’s.

The news comes ahead of the crucial festive period, when supermarkets traditionally enjoy their best sales.

Mr Machin, who has been in charge of M&S since 2022, has made revamping the retailer’s food offering one of his key priorities.

M&S overhauled 1,000 products last year, with bosses saying the aim was to make sure there is a “difference between M&S and the rest of the market”.

The Telegraph revealed in May that the supermarket was planning to upgrade another 1,000 of its best-selling products including sandwiches, cakes and ready meals over the next year.

Other changes include the introduction of market-style stalls into its food halls as part of a ￡500m programme to upgrade its estate.

Clive Black, an analyst at Shore Capital, said: “M&S is really motoring at the moment. It’s travelling at a much faster trajectory than Waitrose.”

He said this success was driven by people doing more of their weekly shop at M&S, rather than buying just a few bits on the commute home from work.

Earlier this year, Mr Machin suggested in an interview that the retailer was monitoring progress against Waitrose.

He said: “You could argue we should have overtaken them already. I might even be arguing that internally here.”

The Kantar figures suggest M&S is beating rivals on both value and volume, meaning the total amount of products it is selling is rising quicker than other supermarkets as well as its till take.

The latest figures showing M&S’s growth came as Kantar suggested that more households were relying on supermarket promotions for their weekly shop.

Spending on promoted items was up by 7.4pc in September, according to Kantar, while sales of full price products rose by just 0.3pc.

Kantar’s Fraser McKevitt said supermarkets were “doing what they can to keep costs down for consumers” at a time when household confidence has taken a hit.

Mr McKevitt added: “In the fiercely competitive retail sector, the battle for value is on.”

Sainsbury’s chief executive Simon Roberts last week said a lack of clarity around Rachel Reeves’s Budget was scaring off shoppers, saying people “inevitably are wanting to be clearer about what’s going to happen next”.