Marsh Lane Allotments in Tottenham are exactly as you would expect. A barred iron gate opens on to a landscape of neat rows of fruit and vegetables interspersed with an idiosyncratic collection of greenhouses and sheds. Exactly as you would expect that is, until, walking down a row of sheds, you come to something that looks oddly like a front door, with the number 94 marked out in mosaic. Step through it, and, suddenly, the vista is very different.