The most obvious place to start was the gallery that ran the length of the royal apartments. A succession of portraits hung between the doors that led off this long passage and windows ran along the opposite wall throwing light on many a royal visage but none of them was my mother’s, at least not as far as I could tell. Perusing the female portraits one by one I kept telling myself that when I saw her I would recognize her but as one face followed another, painted with artistry of wildly varying skill, I became despondent. I had always regretted having no clear memory of Queen Catherine but I had thought I would instinctively know her, that some forgotten but ingrained image would suddenly make a positive match with a picture before my eyes and there would be no doubt in my mind that it was my mother. When this did not happen Harri urged me to think more carefully about what King Henry had said about seeing his mother on the wall.

‘Did he say anything to give you a clue about where it might be? What was he doing when he saw it?’

I told him. ‘We were talking about Queen Marguerite and Prince Édouard possibly coming for Christmas. He said he was worried about the weather. He had climbed a tower hoping to be able to see what the weather was like in the Channel. I thought that was nonsensical, you cannot see that far, even from the highest turret.’

‘Let us search the towers, then. All towers have stairs and a stair has to start and end in a room or passage. There might be pictures hanging there.’

‘Yes, that is a good idea, Harri. When King Henry’s father died his brother Humphrey of Gloucester became Protector and he apparently did not like my mother. He may have hidden her portrait somewhere obscure so that it was not in the public eye. We will ask the Chamberlain.’

It took us some time to find Sir Richard Tunstall who detailed a servant to show us to the hall’s four towers. It was like following a labyrinth in three dimensions climbing one tower after another, winding through all their rooms and passages. Then in the last of the four – inevitably! – there was a portrait that set my spine tingling. It hung in such a dark corner at the base of the circular stair that it was almost impossible to discern the features but even in the deep shadows something about the face made me lift it down from its hook with shaking hands.

‘Harri, Harri, I think this is it!’

The servant carried the picture through the tower entrance and out into the daylight, where we propped it against the wall.