None of the old Brunswicks I saw in the 1960s had heating. There was quite a buzz about heating when three Italian tables were brought to the 1966 San Francisco World Tournament and they were heated.Heated tables have been around for a fee hundred yrs
First electricly heated was used in 1927 in the us, other manners of heating were used before then
So sayeth the Wikipedia
But no so certain how wide spread it would have been in the following 20-30 yrs