There are loads of fancy things that product designers have made over the years, and I like a great deal of them. But I think two of my favourite inventions are the central heating system and contact lenses.

Central heating I imagine was just a very gradual development of different heating methods. But however it worked – it’s fantastic. When the heating comes on on a cold winter evening, you realize how much better you feel. I don’t know how famous writers used to sit crouched over their desks in the freezing cold. How can your brain work when it’s really cold? That’s genius.

The other big favourite for me is the contact lens. Well, two lenses really. You need two, or everything looks very strange. Great invention though, allowing you to see stuff in perfect detail.

Those other things that product designers have come up with – sports cars, fancy lemon squeezers – you can have them. I want central heating and 20 20 vision. That’s what the 20^th Century has given us – and I’m grateful.