A decision to host a six-hour open-air concert at one of London's stately homes has angered residents.
Concert goers enjoy picnics while watching performances
The first Jazz Cafe Picnic takes place at Kenwood House, Highgate, between 1600 BST and 2200 BST on Sunday.
People living nearby are concerned the concert - which they say is double the length of previous events - will set an unwelcome precedent.
Organisers deny the concert is twice as long, claiming rehearsal times have not been taken into account.
Open-air concerts are held at Kenwood House every weekend throughout July and August between 1930 BST and 2200 BST.
This is the first time a concert will have lasted six hours.
Resident, Michael Lyons told BBC News Online that in 1998 an agreement was reached with Camden Council about the length of concerts.
"Ever since, the concerts have operated within these rules," he said.
Organiser, Gudrun Allsobrooke, said the length of concert was not technically double.
"We are allowed to rehearse for one-and-a-half hours, amplified, in the afternoon.
"There is no official rehearsal time, so rehearsals will take place from 4pm."
Rebecca Kane from English Heritage, said that concerts were a way of raising income to keep Kenwood House, which costs £1.3m a year to run, open.