Labour's leadership has been watching Boris Johnson go to work, and they've been learning lessons.
First, they shivered with disgust as his dramatic London win became clear. Then they sat down and started taking notes.
They would have started by looking at a map of how London boroughs voted. The centre of the capital - minus, of course, Chelsea and Westminster - is a gleaming red ball, surrounded by a massive wave of blue in the outer boroughs. The people in those boroughs are the conservative working class and lower middle class who switched to Blair in 1997. They remain the people Labour needs to attract.
And so it was that Gordon Brown revealed a policy on knife crime this week. Mr Johnson's tough-on-crime approach seems to have gone down a storm so far and Labours keen to get in on the act. But the announcement that police should extend the 'presumption to prosecute' to under-18s was described by one advisor as "gesture politics".
It's nothing of the sort. Barristers woke up this morning to find an email from the crown prosecution service (CPS) telling them to go for a prosecution when they find under-18-year-olds with a knife. Previously, youths with knives got about three legal cautions before facing a youth court, the underlying belief being that children should be kept out the courts if at all possible.
It looks like those days are over. Kids with knives will go to court and then find their most common - and probably most truthful - excuse ("It's for my own protection") will automatically make them culpable in the eyes of the law. The prisons are full so where will all these children go?
Quite a number will find themselves given youth community orders, but less lucky ones will end up in prison, before they have even turned 18.
Whether the government is taking this hard-edged approach merely out of Boris-envy or because they, like the public, are genuinely disturbed by the rising tide of knife crime sweeping the country, one thing is for sure: This week saw a real change in the way the government is approaching the problem.