With this knowledge, a person can pretty well figure that the bikes built in India were completly Indian by the late 50s. When they started selling them to civilians is a question I'd like to know. They started exporting them to other countries in the mid to late 1980s. I can remember seeing adds for them in Classic Bike and other rags in that time frame.
The contract for the Indian Army models was originally signed in 1954 and had the Enfield so busy, they were on a 24/7 schedule. They decided the Indians could do their own thing and worked out a deal in 1956 for the Indians to build the bikes. The Indians finally got all the tooling, etc, in place by 1962, after assembling complete kits from England, then working up to only needing engines from Jolly Olde, then complete machines started coming off the line in 1962. They started selling to the public in about 1975, then exports started in 1977 to England and the Continent.
The 500 version was introduced in 1989. Then the US got interested and started slowly importing in 1990. Kevin took over the operations in 1995.
Contrary to some peoples' belief, no other models of Royal Enfield were ever built by the Madras factory. The 350 was it until they developed their own 500.
Bare