Passion flowers are an exotic wonder, and in the warm terraces of London especially, they are known to fruit.
There are two primary varieties, the blue passion flower ('Caerulea') is so blue, it is almost purple. Then there is the white flowering kind, 'Constance Elliot', which is as equally enchanting. You can see why these enticing, winding, floriferous specimens were given the name passion flower.
These vigorous large climbers are deciduous or semi-evergreen in warmer spots, with twining tendrils. They are best planted in a sunny position to maximise flowering and fruiting.