Rolls-Royce chief Tom Purves has told Car Magazine that he thinks his firm might build a battery-powered version of its Phantom limousine. “Many of our customers do small mileages exclusively in the city - for these customers, an electric Rolls-Royce would be ideal,” he told the mag.

Small mileages might be the only option. Given that the 5.8-metre-long limo weighs 2.5 tonnes (including its current 6.7-litre V12 engine) it would need lots of energy and thus a truly gargantuan battery to get it moving.

Apparently Rolls-maker BMW intends to apply lessons learned from its Mini E electric car project. But that car sacrifices half its passenger capacity to make room for a bumper box of lithium-ion cells. Somehow we doubt that a Phantom with no rear seats would be in much demand as city transport for the well-heeled greenie.

There is precedent for this madness, however. UK-based Liberty Electric Cars is converting Range Rovers to run on electrical power, starting with a car that weighs about the same as the Phantom (and which shares the same RR initials, too). Liberty claims a range of 200 miles. We don’t think anyone impartial has actually driven one of these beasts yet, although you can order one if you’ve got £95,000 to £125,000 eating a hole in your trousers.