I definitely remember John Bell Travel (Sunderland) operating the 148, using old Duple coaches after 1986. They built an outstation on a tiny industrial estate on Strangford Road in Seaham, for that and the school contracts they used to run. Now, the 151 was a service which was always passed from pillar to post, along with the 147, 148 and 150. Northern had a stab a few times, the aforementioned John Bell and various others ran them. Ironically, the John Bell then went on to be a depot manager for Classic, then was passed to Arriva. Small world!