The vet has confirmed what I suspected, that much-loved DCat is losing his grip on reality. Health wise he is in good shape for 15.5 years but he gets muddled, messes outside his trays even though they are both fully cleaned at least once a day. I have a Feliway plug-in and have bought steam cleaner to cope with accidents.
Any other ideas to help him (or us) make life as nice as possible for him? TIA 