Was the only tech that worked at the time. Baird was a clever guy with several inventions. He lived locally and sadly died relatively young.
It was the first for sure...
From memory, he persisted with 'mechanical TV' after 'no moving parts electronic TV' was introduced. There were two rival systems but (needless to say) 'no moving parts electronic TV' won the day...
Not sure if I read a book about it specifically or if it was mentioned in the biography of the amazing
Alan Blumlein.