First it was models, now bloggers and sex workers add to the return of unions

They are rabble-rousing roadies and recalcitrant rabbis, reality television stars fighting for their rights and bloggers agitating for job security in cyberspace.

The guiding principles of trade unions providing workers with a collective platform to push for greater working rights may have changed little over the decades. But in recent years the people and professions signing up have become more varied than ever.

Unions are being deluged with membership applications from people in jobs as diverse as the clergy and fashion modelling. Equity, the union that represents performers and artists, last week accepted a number of catwalk queens, including some major "household names", into its ranks.

Gregor Gall, professor of industrial relations at Hertfordshire university, said: "Union membership is light years away from the stereotypical image of yesteryear when the average unionist supposedly looked like Andy Capp, with a pack of roll-up tobacco on the bar and a whippet by his side."

Professor Gall said the labour movement had seen a rise in applications from workers that were not traditionally represented.

In 2000, members of the clergy sought representation to boost their claims for sick pay and annual holiday. Amicus, the private sector union, now represents 2,000 ministers across all denominations and faiths. Most of this membership is based in the Church of England but rabbis have also signed up.

The movement has caught on elsewhere. The singer Billy Bragg and the band Coldplay supported the call for a union to represent the rights of roadies. The Roadcrew Provident Syndicate is now a branch of the GMB.

The GMB, one of the biggest unions in Britain, already has unusual professions on its books including club doormen, sex workers and even a shepherd.

The rise in interest has boosted the labour movement. The GMB, for instance, added 10,000 members last year, and union membership worldwide has gone up by about 30 million in 20 years to 156 million.

Professor Gall said: "That indicates that the notion of employment and work is expanding. Many workers are more conscious of their rights, their threshold to accept poor working conditions has lowered and unions are keen on new members."

Internet workers are also getting in on the act. In November, the National Union of Journalists admitted its first full-time freelance blogger into membership. Jeremy Dear, the NUJ general secretary, said: "Bloggers are looking for the same protections as trade unionists everywhere."

But Equity has the monopoly on unorthodox members. "We are the union par excellence for representing unusual professions," says Martin Brown, an Equity spokesman. "We once had a lady who was called Vespa Goddess of Fire, but my favourite was Ivan Inversion whose specialty was to hang upside down and recite songs backwards."