The object came to within 100 meters of the helicopter. At first, the pilot thought that it might have been a radio control helicopter, but dismissed that idea quietly enough after they used their onboard thermal camera to try and spot any signs of people on the ground with such equipment. The BRITISH MODEL FLYING ASSOCIATION (similar to the American ACADEMY OF MODEL AERONAUTICS) ruled that possibility out due to the high altitude that the helicopter was at to begin with.
Ref. : "UFO involved in a dramatic incident" Birmingham Mail, by Anuji Varma, November 21, 2008. ( http://www.birminghammail.net/news/birmingham-news/2008/11/21/ufo-involved-in-a-dramatic-incident-97319-22310179/ )