A casual glance at reports of the disagreement between the Home Office and Downing Street over stop and search might suggest that the former wants it scrapped and the latter does not.  Such an impression would be mistaken.  Theresa May has said that “as long as I am Home Secretary, the police will maintain their right to stop and search”.  It is plain to see why.  Last summer, she told the Commons that “in the last 12 months, stop and search in London has resulted in 45,000 criminals being arrested, including 3,212 criminals carrying weapons and guns, 7,287 criminals in possession of suspected stolen goods and 1,484 criminals in possession of tools used to steal or cause damage”.

However, these figures are not the end of the stop and search story.  A million stop and searches are recorded each year.  But fewer than one in ten of them result in an arrest – nine per cent, to be more precise.  And the figures show that if someone is from a black or minority ethnic background, they are up to seven times more likely to be stopped and searched than if they are white.

There are two main reasons for concern about the ethnic disparity and low percentage of arrests.  First, it would clearly be wrong for people to be stopped and searched without good reason because of their ethnicity.  Second, for so few stop and searches to result in an arrest suggests a waste of police time.  Furthermore, the disparities between arrest rates deserve study.  In 2011, for example, the rate in Kent was 19 per cent.  In Cumbria, it was three per cent – the other end of the scale.  The rate in London, where most stop and searches take place, was in between: eight per cent.

It is worth following the story in the capital.  The police guidance for stop and search was changed and a target set: that 20 per cent of stop and searches in London should result in an arrest or drugs warning.  The number of stop and searches then fell from 500,000 to 350,000 – but the arrest rate rose to 18 per cent.  Less than a third of those arrested across the country are charged or cautioned.

The most simple explanation of these figures is that the Met is targeting the people who should be arrested, thus using their time more efficiently and improving confidence in stop and search.  As May has said, trust in the procedure is especially low among many members of ethnic minorities.  The Home Office commentary on the figures for the higher ethnic minority stop and search rate in London is gnomic.  “This in part is explained by both the high population density and the high Minority Ethnic populations (resident and visitor) within the Metropolitan Police Service area,” it says. (My italics.)

At any rate, more than a quarter of stop and searches are not being carried out legally, according to HMIC.  So why not seek to export and adapt, as appropriate, the changes that the Met has introduced?  The best explanation to hand is that Number Ten is anxious that reforming stop and search would be inconsistent with the tough message it is trying to project over immigration, crime and welfare.

By contrast, the Home Office and CCHQ are able to point to a different political problem for the Conservatives – and one which this site has campaigned on.  A mere 16 per cent of ethnic minority voters backed the Party at the last election.  Among black voters the percentage was even lower.  The Home Secretary has won praise from the Voice for her stance on stop and search and police custody deaths.  (“Deaths in custody is a problem we need to put right,” she has written for the paper.  “Is Labour losing the black vote?” the Voice asked on its front page last summer.

It will be said that the facts, not political advantage, should shape the policy – not the other way round.  This is right.  But what do the facts suggest for stop and search? The racism charge will be argued both ways but, unquestionably, an ethics and trust problem overshadows the police like a baleful cloud.  At one end of the scale, there is the Mitchell case.  And at the other, Hillsborough, Tomlinson, De Menezes – and, of course, Stephen Lawrence.

The London experience shows that the practice can be maintained and improved, reducing stops and searches but increasing arrests.  Some critics of Downing Street’s position argue that that David Cameron himself and Patrick Rock, the Downing Street Policy Unit adviser on home affairs, are stuck in the 1990s.  The claim is that they have failed to move on from their days as special advisers to Michael Howard when he was Home Secretary.  At any rate, there is a stand-off between Number 10 and the Home Office over how to respond to the consultation that May launched last summer.

Imagine the Party protests were reform held up because of the view of modernisers – despite evidence suggesting that it was right.  The same should be true the other way round.  Stop and search should be overhauled.  When it comes to politics, Downing Street might find that ethnic minority voters would be more pleased and non ethnic minority ones less displeased than it fears.  But either way, reform is necessary.