"An Avro Lancaster Mk III of No. 103 Squadron pauses on the flarepath at Elsham Wolds, Lincolnshire, before taking off for a raid on Duisburg, 26 March 1943. In the background three searchlights form a cone to indicate the height of the cloud base." Avro Lancaster B Mark III, ED724 'PM-M', of No. 103 Squadron RAF pauses on the flarepath at Elsham Wolds, Lincolnshire, before taking off for a raid on Duisburg, Germany, during the Battle of the Ruhr. Three searchlights (called 'Sandra' lights) form a cone to indicate the height of the cloud base for the departing aircraft.