"Brian G" wrote in message
...
GPG wrote:
I'm really talking about the ones at the top which open outwards
about a horizontal axis (I don't know what they are called, sorry).

Top casement sash or hopper sash!

In my neck of the woods (SE) casements are hinged and sashes slide, and
hopper lights are hinged on the bottom rail. The usual name is top lights
or fanlights.