Off and on in the early hours I am aware that Isis is not in the room with me. I vaguely assume she is sleeping in the hall.

When I get up I discover that she is not in the hall. Nor the kitchen. Nor the front room.

She can’t be upstairs. The stairs are narrow and very steep.

Apprehensively I climb them. She is stretched out, fast asleep, on the bathroom floor. The cat food dishes are polished clean.

I take her to the top of the stairs but there is no way she intends to descend. That’s a relief. I’m very pleased that she has sensed the danger.

I pretend to go away so that I can watch what she does. She squirms up the stairs at a rate of knots, looking rather like a hairy caterpillar.

Having discovered that the cat food supply has not been replenished, she stands at the head of the stairs looking helpless.

Once the Polymath has arisen, the stairlift is parked at the bottom of the stairs and will surely deter Isis from repeating her caterpillar impersonation. I refill Daisy cat’s dishes. Silly me.

The rest of the story unfolds fast and is a real photo-opportunity.

Unlike a sighted dog, Isis, of course, is unaware that she is being watched so all of her naughty doings may be observed in full.

After bringing her back downstairs six times, I begin to tire of the game and place a blue box next to the stairlift. This works.

Isis is frustrated. She leaps onto the lift.

Perhaps this will help her to find a solution. Hmmmm.

“Where would I land? Too risky.”

“I’ll sit down and have a think.

Perhaps I could work it out more easily if I moved seats.”

By the end of the evening she solves the problem and climbs over the blue box. She enjoys a second helping of cat food.

The door to the middle room is firmly closed and access to the stairs cut off. She is thwarted at last.

But she has the last laughs. At 2.30 a.m. she barks to go out. We stand in the muddy garden. It’s ink black, wet and windy. Rain trickles down my neck.

When she barks again forty minutes later, I think she ‘s having me on. Bad mistake. I discover in the morning that she was quite serious. It takes a very long time to clean the kitchen floor.

Time to go home.