Hi Graham,
An interesting pair of bikes!
I assume the MT came first for a couple of reasons: the reg number suggests it is a little earlier than the Omega, and for most people the Omega would be a "step up" in the motorcycling world.
This model Metro Tyler was introduced at the show at the end of 1921, for the 1922 season. It was listed as the "sports" model, mostly to differentiate it from the interesting semi-unit-construction model that had been the standard offering from MT since 1919. The engine was MT's own 70x70 269cc two stroke, and the gearbox was either 2 or 3-speed to customer's order.
I wonder if your grandad didn't like it and traded up to the Omega, which seems to be the 300cc JAP four-stroke model. Also a very nice little bike, and probably from around the same 1921-22 era.
Cheers
Leon
