But John was glowing with excitement, his eyes alight. ‘Think what the king will pay for a Semper!’ he said. ‘If it makes two bulbs instead of the one, think what profit we will make. We’ll take it back to Amsterdam and sell it, and we’ll make a fortune and our name as bulb growers. To sell a Semper grown in England on the Bourse itself!’

‘I don’t believe this,’ J muttered to himself. ‘We’ve been scraping the bottom of the barrel to meet the new tax, we missed two months of visitors in the summer because of the plague, and now we are staking eight years’ wages on one bulb?’

John turned to the man. ‘Here’s my hand on it,’ he said grandly. ‘I shall have the money for you tomorrow. Come back at noon.’

For the rest of the day the Tradescants, father and son, called in their debts all around the city, then moved on to favours owed them, and went frankly to the great men in the trading houses and borrowed money, offering the bulb as security and finally selling shares in it outright. Their name was so good and the desire to cash in on the Dutch speculation was so strong that they could have borrowed money against the bulb’s profits twice over. The hysteria in Holland had spread to the whole of Europe. Everyone wanted shares in tulips, the market for which had been rising for years and was rising in great leaps every day. John did not have to struggle to find shareholders in his bulb, he could have sold it outright by midday. By the time they met back at the Ark at dusk they had covered the loan.

John was triumphant. ‘I could have sold it over and over!’ he crowed. ‘This will make our fortune. I shall buy us a knighthood with this profit, J. Your son will be Sir Johnny on the wealth that we have made today!’

He broke off, seeing J’s solemn face and the heaviness of his eyelids. ‘Is it just that you have no zest for anything?’ John asked his son tenderly.

The young man’s face was bleak. ‘She has not been in her grave a year and we are speculating and gambling.’

‘We are trading,’ John said. ‘Jane had no objection to honest trade. She was a merchant’s daughter. She knew the value of profit. Her own father has taken a share in this venture.’

‘I think she would have called it gambling,’ J said. ‘But you are right – I have no zest for anything. It is the heaviness of my heart which makes me think this too great a risk for us, I suppose. Nothing more than that.’

‘Nothing more than that!’ John clapped his son on the back. ‘The profit from it will make your heart light,’ he promised.