Are these two distinct, separate tunes? “Colonel Bogey” dates back to 1914 (with various dubious explanations for its title - mostly referring to golf), whereas the 1958 Mitch Miller version (March from the River Kwai and Colonel Bogey) - has each part with separate composer credits.
From what I gather, “River Kwai” is the background orchestral tune which comes in partway through the whistling. Am I correct? Is there a video/mp3 of just the “River Kwai” tune?
Yes, in this scene where the soldiers are marching into the camp, whistling Colonel Bogey. At about 1:36, Malcolm Arnold’s River Kwai March starts playing under the scene as the whistling continues.
To answer the OP’s question: yes, they are separate compositions. Colonel Bogey was written in 1914 by F. J. Ricketts; the River Kwai March was written for the film by Malcolm Arnold. Arnold wrote it so it would work as a counterpoint to the whistling, but it is also heard in the film without it.
Here’s a nice recording of Arnold’s march, without the Colonel Bogey tune:
Well that was good to learn, because I always thought it was the other way around (ie. the River Kwai march was the first part, Col. Bogey was the part in the middle that sounds like circus music. Don’t know why I was confused).
You will note that in the film, it’s just a brief and messy whistling interlude. It took Mitch Millet to make it a hit that everone remembers.
On his TV show, Mitch Miller usually had a group of 20-25 (male) singers. Does anyone have any idea of how many are actually doing the whistling on his recording? This site mentions that it was recorded in London, on November 11, 1957 (presumably with the Royal Philharmonic Orchestra).
Trivial comment - his recording of the march spent 29 weeks on the Billboard charts in 1958 - longer than any other sing that year.