Hey Trevor S
My Dad was a mod in Notts in the 60's
He has so many great stories about the Mods and Rockers and tells some great stories about a Rocker he calls "RatNeck". He describes him as a scarey bloke who rode an old brit bike with a coffin as a sidecar. In his stories RatNeck kept spanners and wrenches in the coffin and would ride up alongside the mods and through them at their scooters. One time he put a spanner through a Lambretta engine casing. The Rocker in his stories was called RatNeck as he had a neckalace made from Rat tails.
Does this sound like it could be