This is where the true nature of their relationship will be on display for all to see. That, of course, is if Sir Ian is still in office by then.
The noises out of City Hall indicate that the Conservative mayor is trying to oust the man labelled "New Labour's favourite cop".
Whatever the two men's differences are, Londoners can rest assured that both are united in their desire to cut crime on the capital's streets.
Mr Johnson sees having the power to hire and fire the man running the city's police force as a way of tackling the so-called "democratic deficit" and making the police more accountable to Londoners.
Sir Ian said the role of commissioner was losing its political ndependence.
That power currently resides with the home secretary and with a Labour government in office, and so Mr Johnson's best bet may be to hope that David Cameron leads the Tories to victory at the next general election.
Just last week Sir Ian said he was concerned that the role of commissioner was losing its political independence.
Plans to cut knife and gun crime by introducing more handheld scanners and knife arches have been successful so far, with a targeted police operation pulling more than 700 weapons off the street.
The exact manner in which these plans develop may have to be rethought after the London Assembly was advised that the Met faces a real terms budget cut, thanks in part to inflation and rising fuel costs.
Not all Mr Johnson's manifesto pledges are as cheap to implement as the scrapping of the £25 emissions-linked congestion charge or the banning of alcohol on public transport, a policy which he claims has been hugely popular in making London a more attractive city.
Mr Johnson's manifesto also designated crime mapping as another big part of police accountability and it is supposed to be rolled out by the middle of August.
Crime mapping will allow residents to view their local areas online to see how much crime has occurred.
Whilst the mayor was hoping to be first with crime mapping, the policy has proved so attractive that the government has announced a nationwide roll-out by the end of the year.
It does mean another manifesto pledge is fulfilled, but as to whether it will have the desired effect of reducing Londoners' "fear of crime", only time will tell.
The undoubted cloud over Mr Johnson's mayoralty so far has been the Ray Lewis affair.
To have lost the deputy Mayor for young people to allegations of past financial misconduct, less than nine weeks into a four-year term, was a blow for Mr Johnson.
It has left a gaping hole in his approach to an important issue, and is by far the biggest knock he has taken so far. Nonetheless more initiatives to tackle youth crime are promised in the coming months.
Ray Lewis resigned as deputy mayor
That leaves the more minor matters of remarks from James McGrath, a senior aide, which enforced another resignation, and Mr Johnson's very own blunder over the existence of a memo about Olympic overspends.
All of these have given unnecessary ammunition to the mayor's opponents, leaving him with room for improvement.
A difference in attitude, compared to his predecessor, has certainly been evident.
Mr Johnson has not been as keen to preserve the political consensus that surrounded 2012 before he won May's election.
Former mayor Ken Livingstone was a key part of London winning the 2012 Olympics. He saw it a massive opportunity to regenerate a large swathe of the capital.
Mr Johnson appears to have changed lanes, switching the legacy focus from the future of east London to softer areas such as children's participation in sport.
In part this deflects attention from his greatest fear of expensive Olympic facilities turning into expensive white elephants while he is in charge.
The former Eton rugby first-teamer's opening months at City Hall have produced a report warning of dangers about the cost of the venues, the state of security planning and the overall legacy of the games.
CITY HALL RESTRUCTURING
Changes have undeniably been seen in the structure with which the mayor runs London.
A team of powerful deputy mayors and directors of policy have been brought in, mainly from the private sector, for the expertise they can offer to a man who has spent his working life as a journalist and MP.
There is little doubt that Tim Parker, first deputy mayor of London, and arguably now the most powerful man in City Hall, was successful in cutting costs in the world of private equity.
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