From Colt's "A Century of Achievement":
"A Colt has to earn it's V.P.----the "Verified Proof" mark. It is truly a badge of perfection which the final inspectors strike on after they have given an arm a clean bill and license to go out into the world and uphold the Colt reputation for building the world's finest hand guns. But a Colt has to earn it. It must pass every test, every inspection by a good margin or else the V.P. does not go on. The V.P. mark is held in high honor by Colt workmen. They know, better than anyone else, that when a firearm finally gets its V.P it is a true Colt---a thoroughbred."
This is the VP on a Colt 1911A1 manufactured in June of 1941. The T identifies the inspector that did the final inspection and applied the VP.