Temporary events notice: https://www.gov.uk/temporary-events-notice/camden
General guide to festivals and street parties: http://www.londoneventstoolkit.co.uk/
Camden’s guide to holding an event in a part: https://www.camden.gov.uk/hold-event-park
Another guide from LB Camden: https://www.camden.gov.uk/putting-on-event-camden
A general guide to holding a street party: http://www.streetparty.org.uk/
A VAC case study of a local street festival: https://vac.org.uk/case-studies/case-study-lady-somerset-road-street-festival/