Malc, I was thinking maybe altho The article I read was produced in the 70's it may have been in retrospect, possibly in 'Classic Bike' mag.
I also recalled the Triumph Bandit and BSA Fury, a 350cc 180 degree twin. There was an unbadged one stood outside the office in the sub-assembly department. They were the brainchild of Doug Hele and never got past prototype stages before the shutdown. Sadly, no other maker took up the project probly because of the expense of tooling up. No performance figures were published tho' a mag employed an engineer to asess the design and he came up with a top speed of 105 mph, can't recall the 0-60.