Well, Dad and I pulled his Wellbike out of the garage, and took some pics. They're forthcoming, but I wanted to share the markings that were on it and see if anyone had any input.
Machine serial # C5154550
"Use petrol mixture
16 parts petrol
1 part M220 oil
Chassis contract no: 294/23/S1946
Logo on engine is Villiers Junior
On trans case, "Engine Lubrication 1 part Patent Castrol XL oil to 16 parts petrol"
Clutch case "Castrol D Gear Oil" "England"
Engine block, embossed "Villiers Deluxe Junior 8 5784"
Side of block, No XXE3960
It's all original, and really an amazing machine. I hope to post pictures later this week, of the Wellbike, and the 56 Everest, and the 72 Vespa Boxer.