Charlie21 thanks for the pics!
That looks to be a Corsair base with a Silver Streak engine/ engine cover fitted. The Silver Streak base is painted in hammered silver but is otherwise the same as that.
It looks like that base fell victim to a rock strike hence the armour plating. That machine sure looks like it earns its keep, good on you for replacing the rings and piston so it can continue going strong. Too many of my mowers sit for years at a time unused. Your one works hard!
That particular catcher shape is a keeper. They were one of three main catcher shapes that fit on that series of mower base and that moulding seems to be the most hardy from cracking in my observations.
If only Norm K lived within reasonable driving distance from you, as he regularly throws away good bases like yours as he has no use for them without a suitable catcher.

I have a similar mower in my collection called the Corvette with the older non ball bearing wheels. You certainly notice the difference in the pushing. This one is the first series, the mark II got the ball bearing wheels like yours.


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Ahh, if only victa had kept producing the thumblatch catcher series, they would be in better shape today!