Well yes, people vote with their feet. BA (aka London Airways) provide considerably less seats to LHR than say 15 years ago ( A319/320s as oppossed to B757 & B767s).
Hence, people opt for KLM & Lufthansa as connections & the longer haul carriers of Air Canada,American,Delta, US Air, Continental,Qatar, Etihad,Emirates, Singapore & PIA. Nobody really needs to go via LHR these days (thank god).