I did as you suggested and did indeed find several mentions of Churchill using a Colt but in British .455 caliber.
You win the argument as you can support your statement.
I am actually still not convinced that he ever carried one. One of the statements which also gets quoted by other is inaccurate in part of what it states. It says that both Churchill and T.E. Lawrence traded in their M1896 Mausers for Colt 1911s at the first opportunity.
That could not be totally accurate as Churchill had his Mauser taken from him by a Boer and the gun has never surfaced again. But that still makes it more likely that Churchill did indeed have a Colt as he no longer had his Mauser and he probably did keep a gun. That could have been one of his Webley revolvers tho.
“You win the argument”
No argument. Just a discussion.