Nick Clegg has called Boris Johnson a "conventional" politician who "treats his political ambition a bit like he treats his hair."
Clegg said the Mayor of London, who announced his intention to stand at the next General Election, liked to pretend he did not care about his appearance or career - but was actually "fixated" with them.
"The thing about Boris Johnson is despite all the kind of clumsiness and bumbliness, he's actually a really, really ambitious politician," the Deputy Prime Minister said on his regular LBC radio phone in.
"He wants everyone to think that he doesn't really care, but he actually really, really does care."
More top news
In Berwick-upon-Tweed - the town at the northern-most tip of England - history has taught them that no border necessarily lasts forever.
His car was about to get towed away. But he had other ideas.
Our experts take a look at the key issues that would face Scotland and the rest of the UK if Scots vote for independence.