Are the flights to/from Sydney affected by the new rules about hand luggage as they departing/arriving in another country other than the UK (HK)?
Flights Departing From UK Airports to Non-US destinations
All UK departures are subject to the above hand baggage restrictions and security checks.
Books and "dry" duty free goods, such as cigarettes and electrical items, purchased airside i.e. after the airport central security point, are permitted in their original sealed packaging, with proof of purchase. Sealed liquid products, such as suntan lotions, purchased from the airport airside duty free area, i.e. after security, are permitted with their proof of purchase, for flights departing the UK for Non-US destinations.
Regards