I’m overwhelmed with all your responses! Thank you for each and every one of them - and of course I like everything that has been suggested.
I have just purchased some more of the fabric I had thought of using for the frame but I’m now wondering whether to go that way or not and I’m now wondering about changing the colour of the border fabric.
I had also thought of top stitching the borders with contrasting threads.
I think this project will have to be put to one side until I make my mind up.