But on their "Did we call you?" site, British Gas could not trace the number.
I Googled the number too, and found that others had had the same experience. If it was British Gas, why did they not just complete the call when I lifted the receiver, instead of telling me that I had a call waiting? I was there, they could have spoken to me. Whoever it was clearly wanted me to phone them. Why try to get me to do that unless there was some advantage to them - like a premium number?
I don't believe that it was British Gas (or in this case, Scottish Gas) If it was, then they will ring again.