One day she followed a stream for a good half-mile, clambering up the steep, boulder-strewn nullah that guided it down from the peak. It was hard going, with little reward, and she was about to turn back when she looked ahead and spotted a hollow in the hillside, some hundred yards further up. There were white smudges on its sides, and on looking more closely she saw that a cluster of flowering plants was growing inside. She took off her shoes and pressed on, climbing over an escarpment of jagged rock and tearing her skirt in the process. But it was well worth it for she soon found herself looking at a bunch of exquisite white blooms: she had seen their like before, in Calcutta’s Botanical Gardens: they were ‘Lady’s Slipper’ orchids – Cypripedium purpuratum.

She went bounding down in delight and the next day she brought Fitcher with her. This time they went higher still and were rewarded with another find, hidden between two boulders: a pale red orchid. It was new to Paulette but Fitcher identified it at a glance: Sarcanthus teretifolius.

They had climbed a fair distance now and when they sat down to catch their breath Paulette was startled by the splendour of the vista below: the tall-masted ships looked tiny against the blue band of the channel; beyond lay the crags of the Chinese mainland, stretching into the hazy distance.

‘You are so fortunate, sir,’ said Paulette, ‘to have wandered in the forests and mountains of China. How thrilling it must be to botanize in these vast and beautiful wilds.’

Fitcher turned to her with a startled expression. ‘Wander? What can ee be thinking of? Ee don’t imagine, d’ee, that I was collecting in the wild in Canton?’

‘Were you not, sir?’ said Paulette in surprise. ‘But then how did you find all those new plants? All your introductions?’

Fitcher gave a bark of a laugh. ‘In nurseries – just as I would have at home.’

‘Really, sir?’

Fitcher nodded: traipsing through forests was out of the question in China since foreigners were not allowed to venture beyond Canton and Macau. The only Europeans who had seen anything of the flora of the interior were a few Jesuits, and a couple of naturalists who had had the good fortune to accompany diplomatic missions to Peking. Every other would-be plant-hunter was confined to those two southern cities, both of them populous, bustling, noisy places, in which nothing ‘wild’ had existed for centuries.

‘But what about Mr William Kerr?’ said Paulette. ‘Did he not introduce the “heavenly bamboo” and Begonia grandis and the “Lady Banks Rose”? Surely they did not come from nurseries?’

‘Oh yes,’ said Fitcher. ‘They did.’

Everything that Billy Kerr had collected, said Fitcher, indeed most anything that any plant collector had obtained in China – all the begonias, azaleas, moutans, lilies, chrysanthemums and roses that had already transformed the world’s gardens – all these floral riches had come from just one place: not a jungle, nor a mountain, nor a swamp, but a set of nurseries, run by professional gardeners.