Looks like a Royal Enfield model G or J; judging by the oil reservoir fill spout being at the front. I could be wrong of course as I was wrong once in 1948.
Hello Enfield Trial,
Judjing the rockers cover, it's, or a 350cc (G or WDCO), or a 250CC Clipper. The J engine rockers cover is (at bit) different.
Hope it will help you
Claude