The full Press Release on the 2009 Proms, which I have just received, is 3,089 words or 16,480 characters (without spaces) long.
“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.