According to Edgar Wright, the flavour of the cornettos featured in the unofficial ‘Three Flavours Cornetto’ trilogy represents the motif of that film. The red or strawberry flavour in Shaun of the Dead represents blood and zombies, while the blue/original flavour of Hot Fuzz represents the police force. The green/peppermint of The World’s End represents science fiction and extraterrestrial elements.
The reason why the room was pink was because on black and white film, hues of red become dark shades of black. Pink is the perfect balance to give it that dark creepy grey.