George Eustice: Toxic leaks must not be tolerated

Leaks tend to fall into two categories. First, there are those that are hopelessly wide of the mark. They either stem from politicians who are some way from the decision-making process but want to make their mark, or from journalists who are desperate to stack up their own theory. While these are irritating, there is nothing that can be done apart from refute them firmly.

The second type is those that are broadly accurate. They should never be ignored, particularly when they purport to come from sources close to the top. Confidentiality and loyalty to the cause are the most important characteristics of the inner team of advisers for any party leader. You can't function without them. If you wanted journalists in the room, you would invite them.

There will always be certain types of people who can't really cope with being at the seat of power. They can't believe they are there and being in the room gives them a sense of self-importance. Because they are insecure, they also tend to covet the approval of journalists. Such people are psychologically unfit for a place in the inner circle.

I used to apply a rule of thumb that, with hot news, the number of people who actually know something is the square of the number of people whom you think know something, so it is never possible to eliminate leaks altogether. It is also harder in government because not every civil servant supports you. But no government should take a relaxed view about leaks from the centre because they have such a corrosive effect on morale. It is notoriously difficult to trace the source of anonymous briefings but the important thing is to try. You can never allow an attitude to develop where betrayal becomes tolerated. You have to go after the culprits and fire them if you can.

George Eustice is Conservative MP for Camborne and Redruth and a former press secretary to David Cameron.