Just an update.
IT were indeed asked to tweak the system so that the linking of photos did not affect the ranking of "most viewed" photos. I do not believe that the software changes needed were at all complicated.
Shortly thereafter, the direct problem seemed to have disappeared but, despite requests, I have not been told whether any delinking has actually been implemented, or whether the handful of members whose linking was causing concern decided not to do so any more. I think that it might be the latter, so if members see any resurgence, please report back here.