The cat had been acting out of sorts, and suddenly started walking funny. The vets initially thought it was sudden onset athritis, and gave us pain meds for him. A week later, after spending 90% of his time curled up on top of the laptop bag rather than doing anything he starts staggering, walking with an arched back and face to the floor. Turns out he had a large tumour in his spine.
So now he has gone to the big sleep. The weekend has had that slow dismantling of cat-trees and collecting up the various scattered toys and grooming stuff.