Sir Clive Sinclair
Died aged 81.
He had many achievements, including the ZX80 and ZX81, but his most significant computer was the Sinclair Spectrum. I had one, in the early 80s, and it was great fun, and it led me to the IBM PC. I also had a Z88 (I still have that). A brilliant portable computer with an 8 line by 80 character screen, and a built-in word processor and spreadsheet.
He also made an electric bike (the Zike) which was a commercial failure. And an add-on for an ordinary bike that powered the rear wheel with a friction drive. And the C5, which looked like a little car, but was actually a recumbent electric bicycle, and was another commercial flop.
The Spectrum is still alive, via emulators and keen collectors and can be bought on eBay.
I was given a Spectrum by a friend, who thought I could make more use of it than he did. He was right - I dived enthusiastically into the bits and bytes, and found a friend, Mike, who was a fellow enthusiast, and we'd meet for lunch and talk about what we were doing.
One day, Mike told me that he had something even better in his office, and we went there so he could show me. It was an IBM PC running Lotus 123, and he'd set up a complicated model of something, and he showed me how if he changed this or that, the consequences could be seen. As his hands flew over the keyboard, I realised that my friend Mike, who was in no way a programmer, had written a program as a 123 spreadsheet. And I had a blinding flash of inspiration. Everyone would want one of these, because it meant liberation from the "computer department" who usually say "Yes, we can do that, but you have to write a specification for us to follow, we can't start it for the next six months, and it'll take us another six months to complete".
So I knew that I had to get one. Because the Mikes of this world were going to need support, and they wouldn't get it from the computer departments, who actually loathed micro computers (one of them said to me "if everyone has one of these, they won't need us").
And that's how I became the IBM PC guru of the UK.