Harris Mannn was encouraged to go to BMC by fellow Ford employee Roy Haynes who had already been head-hunted to a new BMC studio at Oxford. Mann worked on the Roy Haynes Morris Marina project, but when Roy Haynes left after a disagreement, ADO67 fell into the lap of Harris Mann and he designed the Austin Allegro. Sadly the original sleek design got engineered into something much more chunky. The next design for Harris Mann was the Princess, which he conceived from the outset to be a 5-door hatchback, but was forced to make it a 4-door saloon until the concept was reprieved and the Austin Ambassador version allowed. After the Princess, Harris Mann's 'wedge' theme was given full rein with the Triumph TR7. Then onto more mundane vehicles, with Harris Mann being involved both the ADO74 and ADO88 projects that eventually became the Austin Metro. Finally Harris Mann worked with David Bache on the Austin Maestro project, though Bache generally took charge of this design.