GIVEN the attention focused on Sian Berry, Green Party Assembly member Johnson has had a low profile recently. But insiders say he has been crucial in securing today's decision to urge people to vote "Sian 1, Ken 2". The London Green Party has been split over whether to work with Mr Livingstone, with some believing the Mayor is too enthralled to big business and too enamoured of skyscrapers. But Mr Johnson, the Green mayoral candidate in 2000, has a record of acting in alliance with Ken ever since he won as an independent in his first term. The arrangement even led to Greens winning deputy mayoral posts at the time, but as soon as Livingstone rejoined Labour such formal pacts were off-limits. However, under questioning from Mr Johnson at City Hall, the Mayor has signalled movement towards the green position - a shift that opened the door to today's joint statement.