After Thursday's historic Brexit victory, United Kingdom Prime Minister David Cameron, who spearheaded the Remain vote, has announced his resignation. That means that Cameron's successor is the bombastic former London Mayor Boris Johnson, who led the Leave movement. Here are seven things you need to know about him.

1. He got into hot water for a comment he made about President Barack Obama.

When Obama waded into the Brexit issue and expressed his support for the remain, Johnson went after him in a column in The Sun and pointed out that Obama had returned a bust of Winston Churchill.

"Some said it was a snub to Britain," wrote Johnson. "Some said it was a symbol of the part-Kenyan President’s ancestral dislike of the British empire – of which Churchill had been such a fervent defender."

A number of people accused Johnson's "part-Kenyan" comment of being a racist smear. The Labour shadow chancellor, John McDonnell, called it "dog whistle racism" and said that Johnson should renounce it.

Obama has claimed that the Churchill bust has remained in a private office in the White House, but a British embassy spokesman has said that Obama returned the bust to them in 2009.

2. Johnson and Cameron used to be close friends.

According to The Daily Beast, Johnson and Cameron, who Johnson affectionately refers to as "Dave," were close at Oxford University. But Johnson, "the brighter and more brilliant boy," held a grudge that Cameron beat him to the prime minister position. Johnson may soon get his revenge.

3. Johnson claims to be fan of both Winston Churchill and Margaret Thatcher.

Churchill is a hero to Johnson and he has called Thatcher the "greatest Prime Minister since Winston Churchill":

He has also given an interesting lecture on Thatcher that can be read here.

4. Johnson has an interesting record as mayor.

According to the UK Independent, some of Johnson's initiatives included:

  • Cutting the mayoral portion of the council tax.
  • Raising congestion fees.
  • Introducing "Boris bikes" for taxpayers to ride on, although the result was an overall loss for taxpayers and the new bike lanes have been "frustrating" those who use the roads.
  • Increased transportation fares.
  • Brought in better, safer buses for public transportation.
  • Didn't attempt to fulfill his campaign promise to hammer a "no strike" deal with Tube unions.
  • Crime overall has declined in London, but Johnson did not follow through on his promise to hire more cops and knife crime is still a serious epidemic in the city.

Overall, Johnson had an approval rating of 54 percent as mayor of London.

5. Many within his own party don't like him.

There were a number of people within the Conservative Party who backed Cameron and the Remain movement, and now they're working on a possible "Stop Boris" candidate, which could include chief party whip Mark Harper or Home Secretary Theresa May.

6. He's weak on Islamism.

Johnson suggested that there needed to be an "alternative" word for Islamic terrorism:

The Mayor insisted the police could deal with Islamophobia and intimidation, adding: "It's very difficult to distinguish Islam and Isis, Daesh, whatever - we have a problem in the language.

"When anybody says Islamism, Muslim fundamentalist or terrorist or something like that, the wider public hear the word Muslim - you see what I'm saying?

"So you need to find an alternative word.

Except that Islamism and Muslim fundamentalist are the correct terms, and Johnson sounds like a social justice warrior with these comments.

7. Johnson has been known to change his positions based on political winds.

Columnist Nick Cohen writes:

To Johnson watchers, his shiftiness is no surprise. At Oxford he ran for the presidency of the Oxford Union as a Tory. He lost to a state school boy called Neil Sherlock, a liberal, who secured victory by mocking the old Etonian’s sense of entitlement.

In 1985, Johnson tried again and won, but now and all of sudden Johnson was a liberal too, who was opposed to Margaret Thatcher and in favour of proportional representation. Johnson has ‘no core beliefs’ an understandably flabbergasted Sherlock concluded. He would do anything.

Cohen also points out that when Johnson came out in favor of the Leave movement, his statement left wiggle room:

There is only one way to get the change we need and that is to vote to go, because all EU history says that they only really listen to a population when it says no.

"We will vote to leave, in other words, but we will not actually go, because the EU will give us more," writes Cohen.

Many in the Conservative Party share Cohen's view.