Complex sentence: By May 1910, Claude Grahame-White and other aviation pioneers were flying from the flat areas around Ruislip, though they soon sought an aerodrome for London, which was eventually built at Hendon.
Split into simpler sentences: By May 1910, Claude Grahame-White and other aviation pioneers were flying from the flat areas around Ruislip. They then sought an aerodrome for London, which was eventually built at Hendon.