The characters that Danny John-Jules plays in Red Dwarf and Death in Paradise are so different you wouldn't think it was the same actor. As well, quite some time has passed between his playing the two roles so he looks (and sounds) quite different in each.
However, Death in Paradise is well worth the watching, with good acting, an interestingly diverse cast, clever plots, little to no blood 'n' gore and no offensive language, so it is quite suitable for the younger audience, while being satisfying to the adults.
I get the impression that many British actors are lining up to do at least one episode, as it means a month away on a Caribbean island, and getting paid for it.
Like Silent Witness, it is compulsory viewing in our household.