“Jazz” is just one of those 3,089 words, or four of those 16,480 characters. No words based on the verb root “improvise” appear.
The events I can find are:
1) 18th July : Stan Tracey’s Genesis, as part of a celebration of the 200th anniversary of Darwin in a Late Night Prom, starting at 10.15 pm
2) 31st August: compositions by New Generation artists Gwilym Simcock and Tom Arthurs on 31st August in a chamber music concert at 4.30pm at Cadogan Hall. Programme:
Stravinsky: Soldier’s Tale Suite
Tom Arthurs: And Distant Shore Premiere BBC/RPS commission 2009
Gwilym Simcock: Contours (BBCcommission 2008)
Martinu: La Revue de Cuisine
And that – I think – is all, folks. Out of 76 concerts in the Royal Albert Hall, 19 chamber music concerts at Cadogan Hall, and five BBC Proms in the Park events.