For a lot of Tories, Boris Johnson is effectively the Conservative party leader-in-waiting.
But Boris is a keen student of political history and he looks back at other leaders-in-waiting, like Michael Heseltine for example, who did not seize the crown.
His speech today was quite carefully calibrated: He was funny; He made them laugh; He teased the Prime Minister; He was quite optimistic and buoyant amid all this economic gloom.
But he didn't stray away from his subject - he concentrated on London and he made sure it could not be seen as a direct leadership pitch.
I think it is in his interests to continue like that because if he does the party will be tempted to deploy him quite heavily in the next election.
Boris has pledged his loyalty to the Prime Minister, telling the Conservative Party conference David Cameron will win the 2015 election.
London Mayor Boris Johnson will deliver a keynote speech at the Tory party conference, amid speculation about his leadership ambitions.