Figures from the trade body show 102,138 customers moved from a challenger supplier to one of the Big Six – British Gas, EDF Energy, E.ON, npower, Scottish Power and SSE – last month, the first time in over two years switches to big suppliers have eclipsed switches to small firms.

Peter Earl, head of energy at comparethemarket.com, said: “After years of haemorrhaging customers the Big Six have staged a comeback, clawing customers from smaller and medium-sized energy suppliers.

“British Gas appears to have woken up to the threat from start-up and challenger energy brands, going gung-ho for value with a very competitively priced tariff in an attempt to lure back customers.”

One reason for the move back to bigger firms is a string of small supplier collapses this year.

Toto Energy, an energy supplier with around 134,000 domestic customers, was the latest to go bust last month.

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However, more than 200,000 customers switched from a large to a small supplier last month, around 29,000 fewer than the same time a year earlier.

More than 5 million switches this year

In total, 626,284 customers moved to a new supplier last month, down 1.1 per cent on October 2018.

This brings the total number of switches to almost 5.36 million so far this year, up 9 per cent on the same time last year.

Audrey Gallacher, director of policy at Energy UK, said: “This month’s figures show that consumers continue to take advantage of the increased competition.

“Over 5.3 million customers have already moved to a new supplier and switching is on track to hit the 6 million mark this year.

“With the temperatures dropping across the country, I’d encourage consumers to get in touch with their supplier or have a look online to make sure they’re on the best deal ahead of winter and the cold weather.”