The discovery that Mohamed Ali Harrath has a criminal record in Tunisia and is on the Interpol wanted list because of his links to an alleged terrorist organisation is embarrassing for New Scotland Yard. His recruitment, intended as a constructive initiative, has turned into a potential own goal.

But should we be more worried about Mr Harrath’s background or about the vetting process that enabled him to be recruited as an adviser at Scotland Yard?

The fight against terrorism is not just the job of the police or security agencies. The consequences of terrorism touch all, and so must the responsibility to prevent it.

Communities of contrasting backgrounds, ethnicity and religion need to be involved. Unfortunately, that aim is easier to describe than to deliver.

Some communities remain suspicious of the police and security agencies. Some Muslim community leaders have said to me that they feel isolated and detached from the police. These are hardly the makings of a close working relationship where information and opinions are shared, which is essential if the police are to prevent terror attacks.

The Muslim Contact Unit was formed in New Scotland Yard to help to foster relationships and provide a bridge between the police and hard-to-reach groups. The unit is composed of police officers and community representatives. This combination can unlock some of the stalemates that exist.

The problem is that the very people who are best placed to advise on how to reach those in the community who are most susceptible to extremism are those whose own backgrounds may present a security risk. This is where the dilemma sits. The most valuable advisers are those likely to fail the vetting process and be barred from Scotland Yard.

If the claims about the background of Mr Harrath are true, questions need to be asked about how the vetting process allowed him to be recruited by the Met. But equally it is no good having a vetting process that passes only those who are safe but are not really representative and have limited insights to offer.

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