The Fort School Lisburn

I wonder if you can help me. I have an old school photo which looks around 1920s and have no idea which part of the family it relates to.

Just visible in the top is part of a wall plaque which says Mrs. Gertrude E Keightley, Fort House Lisburn, 22 Oct 1907

Do you know which school this was?

I attach a copy of the photo.

Many thanks
Alan Ellison

If you can recognise this school please email me at