Has Boris Johnson let slip the enormous scale of his political ambitions by comparing himself to the all-powerful wizard Gandalf from Middle Earth?

London Mayor Johnson is usually coy about his political prospects, but that has all seemingly changed with an outburst by him at City Hall.

Under questioning at the London Assembly about low emission zones, the blonde-mopped Mayor insisted he shall be around when they come in to force in 2020.

"In one form or another I will be here," he declared.

"Like Gandalf I will be I will be translated into some new form, more powerful than I can possibly imagine.

"I will be here and we will make sure that under the ultra-low emissions zone there will be no bus that goes through town that is not a hybrid with very low emissions."

Assembly rival Baroness Jones told Johnson he was talking "rubbish," which the Mayor denied by accusing her of the same thing.

The idea of Johnson wielding more power than he can "possibly imagine" suggests he has bigger ambitions than simply being elected as an MP at May's general election.

Canny Johnson has previously played down his own prospects of becoming prime minister by claiming he had more chance of getting locked inside a fridge or reincarnated as an olive.

But death did not stop Gandalf from coming back to life and influencing events in Lord of the Rings, so watch this space.