Just to add a little flesh to the bare bones. London Transport's engineers were still hopeful of developing their own double deck successor to the Routemaster in the late 1960s, but they were up against the perceived failure of the first generation one man operated single deck buses, which brought extra urgency to securing a new omo decker. LT had experimented with both Atlanteans and Fleetlines, but Fleetlines won the day for the production order on account, it is said, of their greater fuel economy. It wasn't to be a standard Fleetline though, and relevant to this thread was London's insistence on designing their own ergonomic cab, with the front incorporating the same type of windscreen as the AEC Merlin and Swift single decks. Bodywork was by traditional London favourite Park Royal, which also built some of those Mancunians, The latter, of course, were a mixture of Atlanteans and Fleetlines, and I'd agree with you they looked better than the DMS from the front, not that either would win any awards for style!
