Complex sentence: Until 2001 the military installation of Porton Down was part of the UK government's Defence Evaluation and Research Agency (DERA) when it was split into QinetiQ, initially a fully government-owned company, and the Defence Science and Technology Laboratory (Dstl).
Split into simpler sentences: Until 2001 the military installation of Porton Down was part of the UK government's Defence Evaluation and Research Agency. DERA was split into QinetiQ, initially a fully government-owned company, and the Defence Science and Technology Laboratory (Dstl).