I found the video on line... go to "metalmalarkey- engineering" click on the video section then look for the one titled "British Bike action" .... bit of a shame that they've now put a sound track to it, when I watched it you just got the sound of the bikes, the triumph and BSA were down at Stafford in 2013 which is when I had a look at them... lovely things, both of them. Anyway check out the video it's worth a goosey.
Cheers, Michael