Their share of the vote only registers in polling data under the rather dismissive heading "others".

Caroline Lucas

One explanation is that hobbles itself with its determination to be different to the other parties - in particular by not having just one leader but two principal speakers.

The party is going to ballot its membership in the autumn over whether to replace that with a single leader.

Derek Wall

This may sound like mere naval gazing, but for both sides it's an issue which goes to the heart of what kind of party the Greens want to be.