The priory church at Leominster is a little bit Romanesque, a little bit Gothic, a little bit Victorian and altogether wonderful. Here's the west window of the south aisle.
The nubbly things studded round the frame and tracery are ballflowers- you see a lot of them in this part of the world. They symbolise the world (represented by the ball) clasped to the bosom of the Trinity (represented by a three petalled flower).
So how do you explain the fact that some ballflowers- not many, but a significant minority- have four petals?
Pretty, ain't they?
Here's a view of the west front.