“The problem with classical music these days”, says cellist Julia Morneweg, “is that it’s too organised, too fixed, and doesn’t leave you room for spontaneity.

“I’d been playing chamber music as part of a piano trio for 11 years when I suddenly realised I was sick and tired of having a work schedule where everything is planned years in advance. Where promoters ring you up and say they need your 2018 programme right now.

“It limits what you do, because it feeds into a system where you’re touring the same handful of programmes over a whole season, playing the music to death.

“And the system also limits the musicians you can play with. I was always meeting interesting new people and saying what a good idea it would be to work together, but never managing to make that come about. Until I found my solution”.

The solution was inspired, says Morneweg, by the contemporary vogue for veggie boxes that people have delivered to their door.

“I had a veggie box delivered”, she explains, “and realised that it could be the model for a different kind of concert-giving. When you get your box you never know exactly what will be inside: you simply trust that it will be good produce. I loved this idea of not knowing. It encouraged you to be spontaneous, to try out different food and ways to cook it.

It set me thinking: how about a chamber-music box that we delivered to an audience without them knowing what would be inside – and indeed, without the performers deciding on the content until effectively the last minute?”

Having been brought up in Germany, studied in Hanover, and then moved to London for postgrad training at the RCM, Morneweg had good contacts among musicians in mainland Europe and Britain.

And her idea was that six weeks in advance of a concert she’d ring round to see who was available, then figure out what repertoire they could offer.

She took the idea to Burgh House, Hampstead, and booked the music room there for a series of concerts running throughout this year that she collectively calls Chamber Music Box

“I have a pool of 14 possible players, and use a maximum of six for any one concert, because that’s all Burgh House can comfortably hold. They’re all brilliant musicians with notable careers, some of them based outside the UK but flying in specially for these concerts.

That’s expensive, but I’ve found we can manage it because audiences to date have been good.

“Although none of them know what or who they’re going to get, they trust us. They have to be open-minded, but that makes them more involved. And they’re usually very grateful. I get people coming up to me incredibly pleased to have discovered a piece of music or a composer that previously meant nothing to them, and that would probably never have attracted them if they’d seen the name on a flyer. It works”.

In fact it works so well there are plans to extend the series next year to a venue in south London.

Realising that she’s on to something, Morneweg is establishing links with local schools to set up similar projects with young people. As matters stand, children get free admission to all her concerts.

The next Chamber Music Box concert is on Sunday May 8, 2.15pm at Burgh House. Or make a date for the rest of the season, they’re July 3, September 25, and November 20. Details – but don’t expect to see what’s on the programme. You find out by turning up.