Any question answered...

Supply and demand. Batteries weren't available because they weren't developed because people didn't want them.

You are mixing up two concepts here. S&D sets price, it doesn't decide possibilities.

Batteries were not developed to the extent that perhaps you would like in the R&D community because the ICE was such a strong proposition and nobody wants to work on stuff they know will have no future at that point in time. Only when several trends converge - the need for super batteries to power the super computer in your pocket, increased awareness of the local environmental impact of ICE, the increasing expense in the production of oil - does the battery vehicle become viable.

And you can't blame consumers for not understanding the art of the possible - I can demand a teleportation system as hard as I want right not but I'm not going to get one, in the same way someone in the 60s/70s/80s could demand a practical battery car with a 100 mile range and be similarly disappointed.

I still think however that if we had vehicles with a 35 mile electric range in the 40s and the same development went into it as has done with ICEs then we could all have had personal EVs with 100 mile ranges for a could £k by now

I agree. But as always, it's worth remembering that while electric cars are undoubtedly more environmentally friendly at the point of use, and reduce carbon emissions overall, they are not really as much of a holy grail as they're being sold as nowadays. The winning strategy is still to go for micro mobility and public transport.