Can you please confirm UK – Beijing – Hong Kong flights qualify for 72 hour transit visas.

My wife is very concerned that para 2 of the Conditions for Application section of your site reads : "If a flight passes USA – Beijing – Hong Kong/Macau/Taiwan, passengers are able to enjoy." Why is USA alone singled out here? Does that enjoyment not apply to journeys commencing from any of the other 50 qualified countries. The rest of your web site seems to indicate the same rules should apply to all 51 qualified countries but, without exception, all of the travel agents in London's Chinatown also adamantly insist UK – Beijing – Hong Kong does not qualify for 72 hour free transit for UK passport holders. Can you please assure us they are all wrong. Thanks.