Originally Posted by
Planespeaking
Ltnman is very generous with his comments. STN, LCY and even LGW were very underused at the beginning of their operation. Those airports were built and airlines did come, in the case of LCY it took several years and false dawns before it became established.
LGW expanded from 1976 onwards with major development of it's terminal and the replacement of the original Pier 2 to accommodate the new generation of widebodies.
HM Government and the BAA wanted to expand LGW as it at the time the airport was seeing considerable increased passenger numbers as London's second major airport.
In 1977 LHR was closed to all new airlines and was seen as full, LGW took up the mantle with ever increasing airlines starting flights with passenger numbers growing.
That was the reason for LGW huge expansion and the airport was already seeing 5 million passengers in 1977.