1928 Phelon & Moore Panthette (Panther) 250cc ohv transverse V-twin.
"At the Olympia Show in October 1926 the Granville Bradshaw designed Panthette stole the attention from every other machine on offer. The Panthette bristled with innovations. A transverse V-twin with horizontally split cranckcase, valve spring arrangement utilising laminated springs, enclosed alloy rocker box, motorcar type 4-speed transmission, multi-plate clutch etc. Only 7 are known to survive untill now." (from yesterdays.nl)