They failed in London in the past because the product they offer is garbage. Qatar, Emirates, Etihad, Singapore all for the last decade have been out doing each other on the product front on the Supers out of all major capitals to Heathrow, in all classes. Qantas stood still and did nothing. The product is embarrassing. The service is rubbish. The entire experience is very inconsistent.
You really need to fly Qatar Suites to really get a understanding of how bad this carrier has become.