Cats are the most popular companion animals in the western world. In the UK their numbers have swollen to more than 10 million. This is great news for the cat lovers amongst us but for those who see Felis silvestris catus as nothing more than a garden pest, it can feel like an epidemic.  Cat Wars meets those on both sides of the feline divide to find out what really gets people so worked up about the humble moggy.  This BBC One documentary also meets some of the more fanatical cat owners out there, including Silvana and her 50 cats and Helen, who likes to take her prized pets for a stroll round the block in a baby buggy.