transit visa to HK for filipina living in madrid

hi, i`m a filipina living in madrid and i have a residence visa here in spain and i`m planning with my son to go to philippines for vacation and i check a fligth to a travel agency and they haved a fligth for us MADRID-LONDON, then LONDON-HONGKONG, HONGKONG-MANILA. i would like to ask if do we need a transit visa to hongkong.THANKS