Just to put the record straight, it was Arthur Lavington, his first name was Edgar but he was known as Arthur when I worked for him in the 60s. Nobody could make an LE Velo go like he could, especially on road trials. One year, he left the line on the Junior and the clutch was slipping. Stopping near Ballacraine, he prised a nail from a fence, adjusted the clutch and continued (You will need to know the construction and working of a Velo clutch ro understand this one.
Check the Manx National Heritage website, go to Collections in the right hand top corner, you will find a fully searchable TT database there.