I was surprised they are still there as I would have thought these two were candidates for a monkey sanctuary(Isle of Wight?) like some of their previous singles.
Either way, much as I suspect it is unlikely, I hope these hang on a while longer as my photographs of both taxa are, frankly, a bit crap obviously there is a slender chance I might see the spot-nosed elsewhere one day, but the crowned is a real last-chance-taxon.
They recently posted 'animal facts' about the Spot-nosed and Lowe's Guenons on their Facebook page, omitting of course that these are old/non-breeding.