Beware of "tilt and turn" windows - this is the type you can tilt open from the top (see photo) - because they are extremely dangerous for cats! Cats can get stuck in the gap and it causes so much damage that it's usually lethal.
I haven't seen these windows in England - I think they're more common in Europe - but I wanted to spread the word in case anyone has them.
I heard about it through a family member whose poor cat died after getting stuck 