I'd have to disagree about Sinclair changing the world of "home computing". That was his aim, to turn us all into geeks who built our own computers and wrote our own software.
But he "failed" and unwittingly (and really really annoying to himself) people bought millions of Spectrums to play computer games.
If you were really into "home computing" there were much better alternatives, primary the BBC Micro and Electron.
His computers were very badly built with terrible keyboards. However the Spectrum had the edge for games because it was much much smaller, cheaper and "packed" with memory.
Sinclair kicked off the games industry in this country but he never intended to and hated the fact.
His main UK competitors at Acorn who built the BBC Micro and the Electron were completely overshadowed by his "success", but had the last laugh later with the ARM processor.
So in terms of home computing (as opposed to the games industry), Sinclair is just a footprint.
What he should be remembered for is the inventor of the pocket calculator. A precursor to the personal devices that now dominate our lives.
Genuinely interesting, thanks for that.