It started in the corner of a beer tent. Now Glastonbury’s Left Field — the trade union-run stage for music with added politics and ethics — is one of the big attractions at the world’s most famous festival.

It is also about to become a permanent national fixture, taking its brand of political culture across the country. Events in London, Liverpool and Brighton have been staged as a warm-up to Glastonbury this weekend and to test the appetite for a touring Left Field.

Its graduation from the beer tent is not only about successful music and cultural promotion, according to Geoff Martin, its organiser, but also about reconnecting the unions with popular culture and, through that, with a younger audience.

Mr Martin said: “It’s been a real tragedy that the trade unions lost their grip on cultural events. A lot of people have a real interest in broad issues, such as fair trade and ethical trading.

“The Left Field can help bring all these together, without ramming politics down people’s throats. But we can’t do that just from Glastonbury, we have to spread the word further.”

Bands and other performers appear free at Left Field, although they are plied with refreshments provided by the Workers Beer Company — the union co-operative that owns 10 per cent of the Glastonbury Festival.

There is no shortage of names wanting to give the world the benefit of their wisdom. This weekend’s crop includes the Rascals, the Levellers, Alabama 3, Reverend and the Makers, Marcus Brigstocke, Tony Benn, Phill Jupitus, former Libertines and now Dirty Pretty Things frontman Carl Barat, and Billy Bragg.

When the Left Field rolls out across the country there will be a strong regional slant, as there was on the Left Field’s opening day at Glastonbury on Thursday with an afternoon from Liverpudlian bands, including a contender for the best-named group the Seal Cub Clubbing Club.

Still regionally, but on a bigger scale, the Left Field will on Saturday put on one of the biggest showcases of Polish indie and pop music in a move to reach out to migrant workers. Polish bands including Alex and the Drummer, Flykiller and Cars on Fire will be introduced by Paul Kenny, GMB general secretary, and Vice-Consul Maciej Mazurek of the Polish Embassy.

Mr Kenny said: “GMB has organized thousands of Polish workers into GMB over the last few years – in particular in Scotland, on the South Coast, and in London and the South East. We want to make sure that Polish workers know that they are welcomed by trades unions into the UK and we want them to be organized against exploitation.”

The GMB and Unison are the biggest backers of the Left Field among the unions with PCS, the civil service union, the RMT and the Fire Brigades Union also playing an active role.

The Left Field, as might be expected, is a not-for-profit organisation. “It is self financing but everything we have in our budget we spend.”

The Left Field is also where the unions set out their stalls in the hope of reaching non union members among the 160,000 festival goers. It is estimated that about half of the total audience will wander through the covered site as some point, possibly more if the usual Glastonbury rain appears.

Rolling out the Left Field nationwide is seen as an increasingly important part of the unions’ drive to re-engage with younger workers. While there is precious little corporate presence at Glastonbury, other, newer festivals are becoming synonymous with their main sponsor such as next weekend’s O2 festival in London’s Hyde Park.

Mr Martin said: “This is one area that the corporates can’t reach, that is just for the unions and other causes. But while we have all the politics and the industrial stuff in there, it stands or falls on the line-up and the ability to draw a crowd.”