Tread carefully with British Gas, they are very spectacularly incompetent, when it comes to legal agreements, Some (many) years time ago, I had a very bizarre encounter with British Gas’s “privacy” policy....
I sold the home I owned, notified them, and billing was all sorted and finalised. All well and good. I was actually moving in with current better half, who already owned another home.
British gas however, transfered the new home account to my name. They said they’d been notified it should be done, but would not say (for “privacy reasons”) who told them to do the transfer. But it could only have been the people who bough my house, a miss understanding, simply notifying them of the change.
Amazingly, they were unable to undo the transfer, despite having no evidence that I ever agreed to it. Took umpteen hours of grumpy phone calls and eventually a written statement by better half, that she was the legitimate account holder, and wanted to remain so.
Emphasise, they are not competent people, and are not nice people.
All of above is of course just my own opinion.