I probably mis-stated the dates.
The Trooper in .38 Special and .22LR was introduced in 1953, the 357 in 1954 and the Python in 1955.
The 357 was discontinued in 1961 and the Trooper in 357 Magnum brought out in 1961.
The 357 was a premium model but it was still a standard production gun. It just didn't get the extra tuning the Super Premium semi-custom Python got.
Compare an early 357 to a Python made in 1955 to about 1957.
For the first year or so, all Pythons were built by two men at Colt.