Here is an official information provided by Zero Motorcycles comapany:

LONDON, (22nd November 2012) – Zero Motorcycles, the global leader in the electric motorcycle industry, recently announced its 2013 model line which features an average power increase of 99%. This means, that all 2013 models are more powerful (the top models Zero S and DS have a peak power 54 PS/40 kW) than the current 2012 models and they all have a continuous power of above 11 kW. This means, that they don’t fall into the A1/11 kW/125cc licence category anymore. All 2012 Zero models (and earlier) however fall into the A1 licence category as no model has a continuous power output of more than 11 kW, even though the top models Zero S and DS have a peak motor power of 20 kW.

People who already have a full car licence may also ride 2012 model year Zero motorcycles after having successfully completed a CBT course (compulsory basic training). A CBT normally costs not more than £100 - £150 and is usually done in a single day. Once completed, a certificate (called DL196) will be issued which is valid for two years (in which time people can take a full motorcycle theory and practical test or renew their CBT training).

Some of the 2012 model year electric motorcycles are still available at Zero dealerships. Therefore, this is the last chance to benefit from A1/11 kW/125cc licence regulation with Zero motorcycles.

Further infomration upon this topic located here: http://www.zeromotorcycles.com/eu/press-releases/nov-19-2012-licence.html