There were several companies at last year's Excel show selling electric MGs and the like....wonder where the ruling leaves them?
Hydrogen can be made from hydrocarbon fuels....for example heating methane with steam and a reaction yields hydrogen, carbon monoxide and carbon dioxide!!!!needs lots of energy and of course you also get other products you don't want.....and not eco friendly at all.
Electrolysis of water will generate hydrogen and oxygen....but you need a ready supply of cheap electricity!!!! So vast solar arrays or hydroelectric plants....or a few nuclear power stations!!!!!
And then you have to store it. It has a high energy density by weight but a poor energy density by volume compared to petrol. Stored in tanks the tank pressure will be 5000 to 10 000 psi meaning a heavy tank! Hydrogen as a fuel in vehicles has been researched for decades but thus far a satisfactory proposition allowing it to replace petrol has yet to be found for the mass market motorist at least....and it's combustion behaviour in an internal combustion engine is very different to octane so running an XK engine on hydrogen will almost certainly cause premature engine failure.
Here is a link to a very succinct explanation for why Hydrogen is not really a suitable replacement for petrol in an internal combustion engine.