Okay, let's talk about the southern sinfonia.

I bet you've never heard them play. I visited their website to see when and where they're playing this year and here is what I found.
Oh shit, not another bloody orchestra doing the last night at the proms! I remember the days when school orchestras used to do this as a fund raiser. I would have expected a little more from an orchestra that boasts being from one of our better known cities. I read the 'about us' section. It was written by Dave Shaw himself. Dave, you certainly have a pompous way of writing.
My suggestion:
Fire Dave, both as a bass player and an article writer, and give the bleeding proms a rest unless you're planning putting on the whole damn thing and not just the last bit.