"There is no one 'perfect' way to care for all cats because every cat and every situation is different. Cats are now increasingly kept as indoor-only pets, whilst many are given access outside or even live outside permanently. It is up to you how you look after your cat, but you must take reasonable steps to ensure that you meet all its needs."
Ironically I found this statement on the RSPCA website. Personally I think it is irresponsible to let cats roam the streets, not only is it dangerous for the cat, it is also dangerous for wildlife. I think if people took as good of care of their children as the RSPCA wants them to take care of their pets, this would be a wonderful world indeed.
also they give indoor care advice her:
Keeping cats indoors - Environment - Cats