Complex sentence: He was promoted to lieutenant-colonel on 30 June 1988 and returned to Staff College, Camberley in 1988 as a member of the Directing Staff, in which capacity he was heavily involved in the modernisation of the Command and Staff Course.
Split into simpler sentences: He was promoted to lieutenant-colonel on 30 June 1988. Returning to Staff College, Camberley later that year as a member of the Directing Staff, he was heavily involved in the modernisation of the Command and Staff Course.