The centre measured 8.5" and needed sufficient adding to it to make it 13.5" square
It is up to the stitcher to work out how to do that - a simple all round border, setting it on point maybe or, as I've chosen, an offset border on just two of the sides
The cream spotted background is the fabric I shall send it on its way with (along with the purple leftovers) to promote continuity
When I first dreamed up my addition I thought I might like to add a little applique to the centre block in the cream - now I really don't know..........
What do you all think?