I did a ex ICN flight to London on my Birthday last year too but I only received 3 cards and 1 box of chocolate (seems OP is lucky)
So my itinerary is below:
HKG - ICN (J) 0100 - 0530 (Card and Chocolate)
ICN - HKG (J) 0800 - 1200 (Card only) and crew even asked if I had got the chocolate in my previous flight and asked me why do i fly on my bday like this (Which i think is pretty mean)
HKG - LHR (J) time forgot - (Card only) but the crew and ISM welcome me on board and keep saying happy birthday and offer me the champagne in F. ISM also came to me and chat with me again before landing on my plan how to spend my Bday in London. This is pretty sweet though.