Original: His father, James Buchanan McAllister, was a British civil servant, originally from Glasgow (where the family still has relatives), stationed in West Berlin since 1969, where he was attached to the Royal Corps of Signals.
Simplified: His father, James Buchanan McAllister, was a British civil servant, originally from Glasgow (where the family still has relatives). He had been stationed in West Berlin since 1969, attached to the Royal Corps of Signals.