In 1934 Royal Enfield experimented with a transverse V-twin 500cc OHV engine with shaft drive! It was abandoned as too expensive. This led to the consideration of a standard V-twin engine with chain timing gear in 1937. This model didn't make it into production either but proved useful in that it silenced widespread criticism of the chain timing gear with its flawless performance. Parts of that timing mechanism, in simplified fashion, were eventually incorporated into the post war parallel-twins.
(Source: "Enfield Engineer" by Tony Wilson-Jones)