Complex sentence: After his retirement from GCHQ he served from 1996 to 2002 as the chair of the Country Houses Association; subsequently in 2005 he was appointed to the board of the US National Biometric Security Project.
Split into simpler sentences: After his retirement from GCHQ in 1996 he served until 2002 as the chair of the Country Houses Association. In 2005 he was appointed to the board of the US National Biometric Security Project.