JACK STRAW'S speech yesterday to the Black Police Association was a realistic attempt to address a seemingly intractable problem. How can government root out the locker-room mentality of far too many of our police? How can a Home Secretary change an institution that seems to turn a blind eye to racial discrimination, racist crimes and sheer incompetence?

A fortress mentality was bound to grow up in a force that sees itself under siege from rising crime: but "getting tough" has all too often meant stopping and searching young men simply because of the colour of their skin, insensitive raids on areas with a large black population, and handing arrests on to a judicial system that is slanted against them, convicting them far more often than it does any other ethnic group.

One reason for this must be the fact that there are so few black and Asian officers. Who can blame them, given the attitudes of their prospective colleagues, revealed in such an unflattering light by the inquiry into the death of Stephen Lawrence? Just 3.3 per cent of Metropolitan Police officers are drawn from the ethnic minorities. That lags far behind their representation in the country, at between 6 and 7 per cent, let alone their far greater numbers in the Greater London area. This fact must play a role in the treatment meted out to black and Asian citizens.

Mr Straw's speech admitted most of this. For the first time, a British Home Secretary has admitted there is something wrong with the police, as well as other services such as the Fire Brigade. This is a breakthrough on a par with the admission of the Commissioner of the Greater Manchester Police, David Wilmott, that his force as a whole was guilty of racism, an admission reinforced by the evidence of other officers The Independent has published. There is no need to get hung up on that term from the Lawrence inquiry, "institutional racism"; all it means is that the police overall are biased, perhaps instinctively, on the basis of skin colour. Recruitment of a different type of officer is a vital first step towards changing that.

Mr Straw, however, has not set targets, or presented measures beyond the most general exhortation. Positive discrimination, a deliberate policy of admitting more officers from the ethnic minorities, would be such a measure. This is not a panacea. It may cause resentment within the force. But it can be justified in pursuit of a higher goal: a truly representative police force, which looks like the nation it serves. Mr Straw has shown that he has the right opinions. Now we need to see whether he has the will to carry them into effect.