An ornate carved pool table. With travelling, I’ve not had a game on it in two years.

My penny farthing. It was £1,200. I’ve ridden it to Buckingham Palace and back.

A snazzy coffee machine that grinds beans and steams milk.

My aeroplane, a Diamond DA42. It’s a twin-engine aircraft and I bought her brand new to fly around the world solo. Very sadly my mum was diagnosed with terminal cancer about six weeks before I was due to take off, in May 2017, and she died early June. After that, I lost interest in doing it.

I'm making cheap electricity,

This light is shining on you. Do you know that it's pushing you?…Most people don't. But it is, because it's got energy. The only thing is, it's so small you don't feel it.

I didn’t realise I’m the oldest ever! So I just about made it, huh? Because you can’t be dead and win … If you’re a winner of the National Inventors Hall of Fame you can be dead. I won that prize a couple of years ago and I was very proud of that. That is the most, I would say, most important prize I’ve won.

I can be cranky,

I invented optical levitation.

I married her because she is smart!