Thanks to Harribobs for an excellent puzzle and beautifuy appealing endgame.
Unfortunately for me, the first 7 or so artists I located were all coloured in in what I'd surmised to be the "key work", however, when I noticed Jean A D ...... in the bottom right is plain white in the work and others where there was no artist were coloured in, I assumed I had the wrong painting and spent an age looking for possible alternatives.
That aside, a great construction and, once again, hats off to Harribobs for a real treat:-)