The two-train watch, the double escapement watch became known as the solar... as the Space Traveller's watch. The watch I'd made for Sam Clutton was also a two train watch and when he died he left it to the British Museum, where it still is, and that was a slight inconvenience to me because I had it in mind to sell the British Museum another watch. Of course, they didn't need it once they'd inherited Sam's and so I had to look elsewhere and even so, I'm very pleased that they've got the watch and they think very highly of it and they keep it on view to the public.

Now, the secret of the success of those watches was the double escapement, which produced a tick-tock mechanism without necessity for lubrication and therefore a better rate of timekeeping for a longer period. But I was becoming more and more interested in the timekeeping of the watches, so the more familiar I became with methods of making them, the more time I had to look around and find ways of improving the timekeeping and lots of little things came along, which I introduced into the watches in order to equalize the daily performance because watches are subject to changing timekeeping for change of position. Difference between being worn in the pocket vertically or flat horizontally, or if worn on the wrist in a hundred thousand different positions every day in agitation as well, and changes of temperature, changes of humidity, all these things affect a watch. And the effects of the changes are very small, and so they're very difficult to eliminate. For example a little watch ticks say 36,000 times an hour and loses a half a second during the day and the half second represents a most minute proportion of the whole timekeeping of the 24 hours, and so it's all the more difficult to detect the cause of it and eradicate it.

It occurred to me that one must try and eliminate these problems one at a time, and the first thing to dispense with was the oil and that had worked well enough. I believed I could then construct another watch to give me the results I wanted ‒ that is, improve timekeeping, plus the tick-tock mechanism so that it wouldn't stop and fail to restart. And so I set to work to devise a new form of escapement, which would give me all the qualities I wanted and yet be simpler than the double escapement watch. And furthermore, I realised that if I could devise such an escapement it was going to have to fit eventually into a wristwatch because the market for pocket watches is very small. It's connoisseurs and collectors who want these watches just for their own personal pleasure. And then outside there's the millions of wristwatch wearers and I must try somehow to produce something that would be available to them.