help with Navy and Gold wallpaper please

[LaurieFairyCake]

I've picked some lovely wallpaper for a room with a high ceiling (9/10 feet) and it has a picture rail all round the top about one foot from the top.

Should I get it matched all the way down or leave the top above the picture rail white

Leave the top of the picture rail white (matching the ceiling).

Does the room have archiving that you can keep matched to the ceiling? If so, then I would go above the picture rail with the wallpaper as it will keep the 'height' in the room.

Yes, it's got coving round the top.

I'm wondering if I only go up to the picture rail if it will shorten the walls (I don't want that)

This room

Only to the rail, and the rail and above should match the ceiling. Or be a single tone darker than the ceiling. That'll make the ceiling appear to be reaching up higher.