Ian, there were two Barton race engines developed by Barton Engineering

There was a 500cc three cylinder which was basically a 380 Suzuki bottom half with heads and barrels designed by Barry Hart grafted on.

There was also the Pheonix 500cc square four that had various developments. I think part of Barton's problems were because no two engines were ever exactly the same. It was this motor that Nigel Rollason used most. He may possibly have used the triple as well, but i'm not sure.

The engine was designed and built by Barry H and Graham Dyson.

The original 4 cylinder development was a stepped cylinder square four which Suzuki brought out a year or so later :? Barton Engineering sued for breach of copyright but it was dragged out by "the big" company.

They, eventually offered to settle "out of court" Most of the money went on legal fees and then Barton Engineering relocated from Liverpool to Caernarvon. The motorcycle engineering side of the business was bought by Armstrongs, much of the new design racing engines and drawing etc. were purchased by Eric Buell (Buell HD now) in America and the rest of the race shop sold to "interested parties"

I have one of the original "works" solo rolling chassis built by Spondon Engineering, one of very few solos built with the four cylinder motor. And as far as I know there is only one complete solo bike in existence, which I believe is owned by John Weedon.

The solo guises, both three and four cylinder models were raced under the "Sparton" name.... Spondon and Barton

Barry Hart still has a workshop in Bolton.