Interesting posts but there is a need to avoid conflating issues here. APD may be excessive and unfair but pricing a BA flight which starts from a non-UK airport and is, therefore, cheaper, is not really an APD issue. Its one of pricing a one-stop option in competition with a non-stop journey. As an example, if you price KLM/AF ex Heathrow in WBC to Hong Komng on random dates over the next few months and compare with similar ex-Amsterdam or Paris, you can “save” about £700 on the return trip. Similar LH through Frankfurt.