Ted Frost was a successful international motocross scrambler, trials rider and Norton works rider in the period immediately before and after WW2.  He owned the Drift Bridge Garage in Reigate Road, just outside Epsom, England. He had become friends with Sydney and his brothers through the Streatham Motorcycle Club, of which they were all members prior to the war.

He persuaded Sydney to build him a J1 for his use. Hence 79J415, the ‘Frost’ Allard, registration number MPG 250, was built and delivered on the 23rd September 1948. It was the thirteenth and last J1 to be made.