Ilford made a variety of colour film over the years....there's lots of info if you Google around.
OTTOMH. there was Ilford Colour Slide (later Ilfochrome?), a very similar system to Kodachrome (I have some slides taken by my late Father in the 1950's and early 60's, still unfaded and rather like the original Kodachrome). Arguably the only Ilford colour film which was up to the standards of the other makes at the same time.
There was a later colour slide film in the mid-late 60's, possibly based on ICI research, not great, even though it was marketed with gimmicks like free slide pages and binders, competitions and a free magazine; it seemed rather dull and "muddy" certainly not up to the equivalent Kodak and Agfa products of the time.
There were various colour negative films, again not really up to the "big makes" of the same era, and I believe that their last 35mm negative film, before they withdrew to all B&W, was an "own label" from Konica. Apart from this last product, I believe that all the films had their unique processes, at a time when standardisation to E4 and C22 (and subsequently E6 and C41) was becoming the norm., so probably not popular with photo labs.
Oddly enough, there were some illustrated "Ilford" books of garden and house plants published in the late 1960's, with all the pictures taken on Ilford colour film.....I have a couple of these, and, TBH, the pictures are not really much of a recommendation for the film !