The Conservatives' changing green image

April 2006: David Cameron wears a green tie as he launches the final phase of the party's local election campaign focussing on green issues at the Conservative central office Photograph: Dan Chung/Guardian

April 2006: The future prime minister makes a speech on the party's local election campaign focussing on green issues at the Conservatives central office Photograph: Dan Chung/Guardian

April 2006: Cameron loads up a van before visiting Brentford to distribute information packs on local recycling schemes Photograph: Bruno Vincent/Getty Images

July 2006: Cameron cycling to work through Hyde Park, London with future chancellor George Osborne Photograph: Rex Features

April 2006: The Conservative party leader visits the Scott-Turner glacier on the island of Svalbard, Norway during a trip in which he saw the effects of climate change – a key moment in his strategy to de-toxify the Tory brand Photograph: Pool/Reuters

October 2006: A man walks past a Conservative party sign at the party's annual conference in the Bournemouth International Centre Photograph: Daniel Berehulak/Getty Images

October 2006: The new Conservative party logo – another significant moment in Cameron's 'greening' of the Tory brand – is stuck to a wall at the party conference at the Bournemouth International Centre Photograph: Bruno Vincent/Getty Images

October 2006: Cameron launches the 'Can I have the bill please?' campaign in London. Both Tories and Lib Dems put pressure on the then Labour government to introduce a climate change bill Photograph: Scott Barbour/Getty Images Europe

March 2007: A workman erects a new wind turbine on Conservative leader David Cameron's new house in west London Photograph: Andrew Parsons/PA

July 2007: Cameron delivers a speech on effective discipline in schools at the Policy Exchange in London. The previously green tree logo behind him has now turned blue Photograph: Lewis Whyld/PA

October 2007: The scene is set for the Conservative party conference in Blackpool. The green tree is back – for now Photograph: Graeme Robertson/Guardian

October 2007: Cameron addresses business leaders in London – with the green logo Photograph: Peter Macdiarmid/Getty Images

October 2009: Cameron addresses delegates at the Conservative party conference in Manchester. No sign of the party's green branding Photograph: Dan Kitwood/Getty Images

October 2009: Party leader David Cameron delivering his keynote speech at the party conference in Manchester Central. Again, the green tree is absent Photograph: Christopher Thomond/Guardian

April 2010: The green tree makes a return during the election as it appears on Conservative party election signs – here competing with rival Liberal Democrat ones in Bristol Photograph: Matt Cardy/Getty Images

October 2010: A girl walks past a Conservative party poster, holding a balloon in Birmingham, England. The green tree has been transformed again Photograph: Dan Kitwood/Getty Images

March 2011: Conservative party spring conference at the SWALEC Stadium, Cardiff, Wales – with the green tree adapted for a Welsh audience Photograph: Richard Gardner/Rex Features

March 2011: No green logos as prime minister David Cameron addresses the Conservative spring forum at the Welsh Conservative conference in Cardiff Photograph: David Jones/PA/EPA