Always felt it a huge mistake that with so much discussion both inside and outside the house over who may be the next Head of House they dropped it completely after week 1. They had the opportunity to build on that after BB9 and possiby introduce it properly in BB10 but they didn't and the show got axed instead.
For all the credit BBUK got at it's height one thing they were guilty of it not building on often well received format points or themes, usually just starting from scratch the next series instead. The only series they really did it was BB6, building on the evil theme but giving it the twist of secret missions. The accompanying Celeb series to BB5/6 built on the main series well too.