Octopus Energy has signed a deal with Shell to buy its UK energy arm, meaning one of Britain’s most popular suppliers will now power almost one in four homes.

The deal will require regulator approval and Shell customers were advised to “sit tight” for now, with it hoped to be formalised in the final quarter of the year.

Octopus has the highest approval rating of any UK energy supplier according to a Bain & Company survey recently, and has been Which?’s Recommended Energy Supplier for six years running.