Tommy felt himself getting drowsy, and the Duke looked as if he had already fallen asleep. It was a perfect English summer Sunday.

But idylls did not last, and this one was abruptly ended by the arrival of a hungover King and his immaculate female friend.

The Duke and Tommy got to their feet and bowed to their sovereign, while the Duchess performed a perfect curtsey. Mrs Simpson ignored it all, heading to a chair under the shade of the parasol.

The King, in dark glasses, was ordering a drink from Ainslie.

‘A Bloody Mary – large.’ Stubbing out his cigarette, he lit another and sat down in the chair Tommy had just risen from. ‘And a dry martini for Mrs Simpson.’ He rubbed his head. ‘I have a headache.’

After a slow train journey, Tommy was back in London, in his rooms at Buckingham Palace. He divested himself of his clothes and put on his dressing gown, a gift from Joan. He missed her and the children dreadfully, but he also prized the solitude of life he led without them. He often felt torn between the two.

Sitting at his desk he pulled out a sheet of headed note paper and began to write.

Darling Joan,

I have just returned from Royal Lodge. Excellent lunch as always – poached salmon and new potatoes, then summer pudding. The Yorks were charming.

However, the garden was a disappointment, the lawn suffering without water. I found myself wanting desperately to be back in West Sussex. By the way, how is the Dahlia v Earwig contest going?

But you won’t want talk about earwigs. You want to hear all about ‘a certain person’, as she is known at BP.

The King was hungover and chain smoking. Nothing new there. He was pleasant enough and his family appeared happy to see him, but I detected several degrees of concern. He is very thin and tired-looking. He ate very little of the excellent food and smoked throughout lunch.

The Duchess was warm and amusing – you know how engaging and supportive she can be – but I saw one or two expressions of disquiet cross her pretty face. There is a tough woman behind her soft exterior. She remained cool, hiding her emotions admirably.

The centre of attention was, of course, Mrs Simpson. She was totally at ease, so much so that she took the hostess’s chair, at the head of the table.

The Duchess, with perfect manners, did not turn a hair as she took Mrs S’s allotted seat. Ainslie, poor man, was puce with anxiety about where the King would sit. To Ainslie’s relief, he did not take his brother’s seat but settled where he had been placed.

I had the feeling that Mrs S’s faux pas was no mistake. She is very slender with a sharp face and dark hair pulled back to reveal hard eyebrows, rather pained eyes, a large nose and a thin, lipsticked mouth. Her jewellery, however, was exquisite: a gem-encrusted bracelet, three rows of very good pearls and diamond drop earrings. I have no doubt they have been gifted to her by the King.