Bee falling out of flower

I've always liked these flowers, although the plant itself is a real pest. It is Hedge Bindweed (Calystegia sepium) and I like the pure soft white of the petals, and the white stamens and anthers.

The bee went in head first and then turned itself around in the flower, with difficulty, before almost tumbling out again.

It was very windy and I had gone out into the field because I had seen an Emperor Dragon-fly about but it didn't re-appear for me. The bindweed is all over the bushes that make up the hedgerow at the back of our garden, together with wild honeysuckle - all lovely for the moths and bees.