I had a discussion with their historian about the design background of Chislehurst. The club has always believed that Colt was involved, but the hard fact is that there is no evidence to support this conjecture.
The club was founded in 1894, a nine hole course. Obviously too early for Colt involvement, he was studying for his solicitors exams in London at the time. It was extended to eighteen in 1900, with a member, Easton Devonshire, generally regarded as being responsible. Again, no real possibility of Colt involvement; he was working as a solicitor in Hastings, although by then he had clearly decided he wanted to be a part of the nascent golf business, given his application in 1899 for the R&A secretary's job.
The final major alterations to the course were in 1913/4, and are credited to James Braid. It is not impossible that Colt might have had some involvement in this work -- I have a couple of examples of courses where he and Braid were both involved. But there is no prima facie evidence that he did.
To quote club historian David Hatton (who I thank for his help): "We are not sure how this speculative link between our course and Harry Colt started, but the bottom line is that in our research we could find no evidence of any connection."
Conclusion: unless evidence emerges, NOT COLT.