Castlereagh leaned towards him. ‘Odd, ain’t it? You fight the French for over twenty years, and then they greet you like a hero.’

‘Peace and deliverance from tyranny are apt to make one cheerful,’ Arthur replied drily.

‘Indeed.’ Castlereagh waved to the crowd, and drew a fresh cheer from them as they waved hats and coloured strips of cloth in a shimmering frenzy. His expression hardened briefly. ‘Then ’tis a shame that the new King of Spain has failed to learn the lesson. You have heard of the troubling situation in Spain, I take it.’

Arthur nodded. On his return from exile at Valençay, Ferdinand had immediately set about imposing his authority in the harshest possible manner. All the reforms that had been instituted by the Cortes had been overturned and those who protested were thrown into jail. It was a hard thing for the Spanish people, who had fought one tyrant for so long, to have another imposed upon them.

‘Very well, then,’ Castlereagh continued. ‘I shall need you to go to Madrid as soon as possible and try to talk some sense into the King.’

‘Me?’

‘Why not? You are the man who liberated them from the French, after all. You have more moral authority there than any man I could send, and, I dare say, more than even their new King.’ Castlereagh paused to smile brilliantly at a distinguished-looking woman watching the procession from a balcony. ‘Madame de Staël. A brilliant mind, that woman. You must look her up when you return here to take charge of our embassy. Speaking of women, you must be looking forward to seeing that wife and those sons of yours, eh? First time in years. By God, your boys must have been infants when you left.’ Castlereagh glanced at him with a kindly expression. ‘I fear you shall be as a stranger to them all.’

Arthur thought a moment. The prospect of returning to Kitty troubled him. He had been a soldier for far longer than he had been a husband, and he feared that peace would make the strains of their marriage unavoidable. He cleared his throat.‘I will see to my men at Bordeaux first. I owe them my thanks, and I must see that they are returned to Britain as swiftly as possible. Then I shall return home to my family.’

Castlereagh looked surprised, and then shrugged. ‘As you will. Though I dare say that your nation will want its share of you before you can be allowed to enjoy the privacy of family life. You must know that all England holds you in far higher regard than even these people.’ He gestured at the cheering crowd. ‘Best get used to being the darling of the public, Wellington.’