This is a bit of a reach, but I will give it a shot. The firm Mulliner (not directly related to H.J. Mulliner. Arthur Mulliner, or Mulliner's of Birmingham) was/is located in Liverpool, very near the Bentley plant in Crewe. While the name Mulliner is very well known in coachbuilding, this particular firm is not as well known, did/does specialty work for Bentley, has a name that begins with M, and a name that has eight letters. So, how about: 1929 Bentley Speed Six by Mulliner?