Chelsea, the most famous flower show in the world, pulled in its devotees once more this week, with its accustomed mixture of colour, scent and glamour. The continuing success of the Royal Horticultural Society’s ‘flagship’ show has much to do with the BBC’s need to fill schedules, the foreign media’s enduring fascination with ‘Englishness’ and royalty, and the desire of committed gardeners to worship in the company of their co-religionists.