Complex sentence: The British Hawker P.1154 had been cancelled in 1965 by the government before a prototype had been built, though its subsonic brother, the "Kestrel" VTOL fighter was flying in trials with the US and West Germany.
Split into simpler sentences: The British Hawker P.1154 had been cancelled in 1965 by the government. Its subsonic brother, the "Kestrel" VTOL fighter was flying in trials with the US and West Germany.