The difference between my two Owls is very clear. Just as Hilary's my female is less white in the face, more grey. And the male his rings around his belly and neck are wider.
Here it's normal to give only the male an extra band, than it's easier to see.
I told some weeks ago I put the pair outside, well, I promised myself to keep my eyes on them, to avoid nestling and laying, but I failed. I saw them sometimes with grass in their beak, but all my birds do that so I thought 'no big deal'.
The hen sits now inside after I found her trying to get rid of an egg. She is definetely too young
Inside she laid two eggs and now she's calling for her male all the time.
The cock sits outside and sings all the time or jumps up and down with grass in his beak...
Later today (or tomorrow) I can hopefully rejoin them in a new builded breeding cage.
So Sally, if hou have a strong pair, it's maybe an idea to put them one by one in your flight cage? If you wait a day or so before putting them together you can easily find out which one is singing.
PS I added two pics of my Owls at the gallery