It would be insane to start an EV company in London. Rent and rates are cripplingly high and you could get considerable tax incentives for setting up elsewhere in the UK.

Nissan have recently opened a massive battery factory in Sunderland to complement their existing car factory. Jaguar Land Rover have announced electric models for 2017 which would be manufactured in their Birmingham, Halewood or Solihull factories. Magtec in Sheffield and Zytek in Staffordshire design and manufacture electric drivetrain systems for a number of companies.

London =/= Britain.

Because companies grow out of the environments that surround them. London depends heavily on public transportation, so I wouldn't expect to see much innovating in the automobile industry there.

True. But electric vehicles (milk floats, buses, trains, trams, underground trains) have been used for a very long time. Since 1890 for tube trains, for example.

England's electric vehicle companies would tend to be located in areas that had heavier engineering - electric trains were built in Birmingham

There's Global Electric Vehicle Corporation.[1] It's a classic startup. Cool web site, new marketing concept ("white label" electric vehicles), hip features ("not just a car, an eMobility vehicle designed to meet the lifestyle needs of today's electronically wired and iPod generation"). They're not actually shipping cars, and all the images of cars seem to be renders. But their web site is really cool.

(Although they're in the Midlands, not London.)

[1] http://www.globalelectricvehicle.com/

While not a fully-electric vehicle, the McLaren use some interesting battery tech in their P1 road car and F1 cars.

This is because they can only historically be in Woking.