A breach of the new legislation could lead to imprisonment

The new laws have been introduced region-by-region, reaching London last.

To qualify for a licence, door staff must have their identity and criminal background checked, undergo training and sit exams with an accredited firm.

They must clearly display their licence badge when working. Any establishment employing unlicensed door supervisors risks losing its premises' licence.

Nationally recognised

The door supervisors' licence costs £190 and lasts for three years.

It is the first nationally recognised qualification for door staff, who until now have been regulated by local authorities, if at all.

Door supervisors are there to keep people in the club, not chuck them out Peter Ruggerio Door supervisor trainer When bouncers kill

As well as passing security checks, door staff now have to train in key areas like conflict management, drug awareness and coping in an emergency.

Door supervisor trainer Peter Ruggerio told BBC Radio 5 Live attitudes towards going out at night and the old stereotype of bouncers had changed.

"Door supervisors are there to keep people in the club, not chuck them out," he said.

Mr Ruggerio said licensing gave credibility to the industry and that, from his experience of training door supervisors, it would be effective.

"The response I think has been very, very good."

Licences are mandatory for staff responsible for security, protection, screening the suitability of people entering the premises or dealing with conflict in pubs, clubs and other licensed premises open to the public.

A breach of the licensing laws under the Private Security Industry Act could lead to up to five years imprisonment and an unlimited fine.