The only way to keep a garden in central London thriving in summer is to use containers, and pray for rain. My expat life never really allowed my neglected plants to thrive in Marylebone. So here are some photos of windowboxes and tubs that have been nurtured more carefully by local gardeners.
Keep it simple, bright and sophisticated, and you will meet the Marylebone standard.
And beware of plants that want to take over the world.