I just happen to have a Summer 1969 ABC to hand. All services at LBA were operated by Viscounts (BKS, Channel and Aer Lingus) except for BUA Heralds to IOM.
Sorry, that's not an answer to the question that wasn't asked in the first place.
Just to get back to One-Elevens, I saw BUA's first one, brand-spanking new with the paint still wet, at Heathrow of all places.
Edit: oops, this isn't the 1-11 thread. Never mind