One of my students asked whether she should describe the ordinary house in which her character lives. She could see that somewhere exotic like a fairy kingdom needed describing but the house in her story was more or less like her own childhood home and she was afraid to bore the readers with it.

Whenever I get a practical question like this, I try out the solution before offering it. It’s surprisingly easy to tell people to do something and then find you can’t do it yourself. So I looked around at my own house to see how easily it could be described.

It is some years since my children left home. In their absence the house became very neat, very tidy, very professional-looking. The walls were all painted in Farrow and Ball colours, a grandfather clock ticked comfortably in the dining room. There were flowers in a vase on the bureau.

Then the grandchildren arrived. Very soon there were crayon marks on all those white-with-a-hint-of-posh walls, hand prints on the windows, face-prints on the mirrors. Alcoves where reading lamps had stood were now stuffed with garishly-coloured plastic toys, wooden bricks poked out from under sofas. Children’s beakers littered the sink.

The house could very easily be described, I realised, though it would not necessarily make the kind of picture I had aspired to when I had imagined the calm waters occupied by those happy individuals whose children have reached maturity and are at last able to arrange their own affairs.

I stood in my living room recalling the way our youngest grandchild had repeatedly puked up her milk in her first few months and I knew exactly what I would tell my student – that every carpet has its own stains, that even the hieroglyphs that decorate the Egyptian pyramids do not have a richer story to tell than the crayon on the walls of my hallway, and that, however familiar it might seem to you, there is no such thing as an ordinary house.