Tomorrow evening on BBC2, we will see Gareth Malone - classical music's preppiest and cleanest-shaven champion - face his greatest challenge. He won't be bringing Puccini to Peckham or persuading ASBO teenagers to embrace choral singing, but attempting to convince television viewers that Glyndebourne is not the elitist institution we've been led to believe.

We follow Malone on his latest mission - recruiting and training a chorus of rowdy teenagers for Knight Crew, Glyndebourne's latest educational opera project. The formula is similar to Malone's previous series The Choir, but it's the program's secondary agenda that is most interesting. As Glyndebourne's director, David Pickard, explains:

A lot of people out there know exactly what Glyndebourne is - it does these lovely operas. Everybody has a picnic and they all dress up. Actually it's so much more than that.

In a political environment in which even the Proms face charges of "elitism", country house opera with its black-tie dress code and conspicuous champagne consumption has long been the mad wife in the cultural attic. The glossy image of the big three - Glyndebourne, Garsington and Grange Park - has been both blight and blessing, the cachet ensuring a steady flow of private funding but also allowing these institutions to be dismissed as culturally conservative and nostalgic.

A glance through past seasons' programmes however is revealing: far from sticking to the safe ground of Figaro and La Bohème, the major institutions have deliberately pursued a progressive artistic agenda, "branching out into more esoteric repertoires", as the veteran critic David Nice puts it.

Quietly racking up a disproportionate number of UK premieres and rarely performed productions, these institutions are guaranteed audiences almost regardless of musical content thanks to long-term (and expensive) membership schemes. It allows them an artistic freedom that publicly funded institutions such as the Royal Opera are denied.

Glyndebourne, for example, can choose to champion obscurity or novelty, to program a season such as 2002, which featured Weber's Euryanthe, Gluck's Iphigenie en Aulide and Janacek's Katya Kabanova - a daring (and, as it proved, fairly disastrous) collective line up no government-funded institution would even be able to contemplate. Indeed, one of the first reactions to last year's economic straitening was a Royal Opera House proposal to scrap a new production of Prokofiev rarity The Gambler.

This season alone sees a much-hyped UK premiere of Rossini's Armida at Garsington, and performances of Richard Strauss' Capriccio together with Prokofiev's Love for Three Oranges at Grange Park - two works that have not been staged professionally in England for over ten years.

Yet what of the audience in all of this? Despite extensive outreach programs and reduced-price ticket schemes targeting younger opera-goers, the basic demographic has seen little discernable change. Artistic progressiveness does not, it seems, necessarily promote social mobility. Prohibitive ticket prices - so essential to the survival of these companies - continue to work their narrowing effect

Central to the ethos of country house opera is the idea of opera as a social experience - art embedded into broader human rituals and rhythms. A public genre almost from its inception, it was only in the 20th century that opera became isolated from mainstream culture. Look for an equivalent of Handel's raucous King's Theatre - a place as much for business, socialising and gossip as art - and you'll find its equivalent more readily in the leisured process of Glyndebourne than the efficient formality of the Royal Opera House.

With cuts to public arts funding imminent, and Conservative talk of a move towards a "US-Style culture of philanthropy", it seems a good time to look to at the unique artistic model of country house opera - to try and translate this crucial element of its structure back into the bigger halls and broader audiences of the public sector.

Gareth Malone goes to Glyndebourne is on BBC2, Thursday 17 June, at 9pm