Thats Dick Mann's BSA Flat tracker, Oh the temerity to mock "The Mann". Even in his senior years leaves the punters in the dust. (I once followed him around a race track up in Washington state, what little I could see of him disappearing in a cloud of flying dirt on a AHRMA MX track, I am humbled to have even been in his presence) The man is a class act.
I have one of these in project form. One of the other list members here and on BritBike has confirmed the motor has competed on a national level and gave me the dates and rider. The motor came from a Calif Racer, its been somewhat modded.
If you look around there is official BSA Blue prints on the frame construction, also Ray Hensley built a limited number of rigid and swing arm Trackmaster frames as well. Assuming you lot have heard of Track master?
I did not have the opportunity to discuss at length with Mr Mann, he is shy and quiet unless he knows you well and I dont have that privilege but he seems to have migrated away from BSAs and instead rode Monarchs when I saw him, The Swedish? Version of a Goldstar.
I also have some history of him in the early 1960s in a article I wrote for Old Bike Journal about the Indoor speedway bikes on a circuit here in the Pacific NW,, Stripped down Speedway bikes racing with no brakes on Polished Concrete floors in a variety of venues including here in Portland Oregon. Back in the day Sports journalists had a interesting bit of flair in their writing and nicknamed him "Spoke Speedster" and the rest were "Cycle Aces". I have photos and period news clippings thanks to a local historian of MC racing Jim Skinner who restored one of these bikes called "Saturday Night Slider" A stripped down and hot rodded Triumph Cub.
Dick Mann rode a borrowed one often but it was problematic for a BSA Sponsored rider to mount a Triumph in competition but no one lost their mind over it. Im including the "Right Mann" himself,, aka "Mann of his time" (A great book under that title, well worth a read!) Showing proper form and technique.
Also here he is with a Swing arm Trackmaster as well.