Do we need visa??

Hi, my wife an I are on a anniversary trip an this is our flight itinerary; London Heathrow - Bangkok - Phuket- Beijing - London Heathrow. Our flight from Phuket to Beijing is with Cathay Pacific, en route to Beijing we have a one hour 15 minute stopover in Hong Kong where we change planes and carry on to Beijing. We arrive in Beijing at 21:10 on 01/12/15 and depart to London at 12:30 on 04/12/15. Do we qualify for 72 visa free please?
Thanks
Brett, London