Given that the terminal is close to if not more than 50 years old. I remember spending quality time in the D or E pier in the early/mid '70s when a SQ 747-200 had to have an engine or something heavy and a/c related removed from the hold. Did't know ore remember the exact details but it required not loading a lot of bags at LHR where the flight originated - thankfully my family knew the SQ station manager at LHR who made sure our bags got loaded.