I'm arriving at Heathrow T3 from Singapore, then going onwards on a UK domestic flight from T5.
As its a domestic flight, can I bring my duty free from Singapore (in sealed bag etc) on to that BA domestic flight in my hand luggage? I didn't think it would be any problem until I saw a post somewhere on trip advisor saying I couldn't as its still a transit flight. My checked baggage will be going all the way through from Australia, so no chance to put it in there.
Or (and I didn't think this would be the best option but others may know better) could I get the duty free on arrival at Heathrow to carry on? I haven't transited through Heathrow before, it's always been Europe where I know I can't carry it through from Asia to the UK.
Thanks in advance