This month we start a series of blogs on garden design for different shapes or sizes of garden, and we begin with a British classic: the long narrow garden. One person’s problem is another person’s opportunity, and so it is with gardens. Some people complain about having a plot that’s nothing but a boring corridor, others see a long, narrow garden as a chance to come up with a creative design. We prefer the latter mindset. It’s become a bit clichéd to talk about ‘spaces’ and ‘rooms’ within a…