Yesterday, Dyson dropped the bombshell news it is canning its car project because it isn't financially viable.

Yes, there had been long-term doubters, unimpressed by Dyson’s financial commitment to the project and disbelieving that James Dyson and his team of 500 or so engineers could realise something that tens of thousands of brains at established car makers couldn’t, even while spending budgets 10 times the size of his.

But this was James Dyson, a man who has amassed a personal fortune of billions through being smarter than most, and by taking engineering prowess and marketing genius and wrapping it up into products that change industries.

Now, we know the reality, albeit with one crucial missing detail: why? What led Dyson to conclude - around a year from the first car going into production and 18 months from the car going on sale - that the project was no longer financially viable?

Here are three theories put forward by experts Autocar has spoken to since the announcement.