I looked up at him. ‘But the lock is surely new.’

‘Yes indeed. When the hunt for heretics and the questioning of those within the royal household started this spring, the Queen had the locks on all her cupboards and coffers replaced. I asked if she wanted a more complex lock for this one, too, but she said it might damage the coffer. I remember her telling me, “If I have the only key and the new lock is strong, surely it is safe.” ’ ‘Of course,’ he added, with a note of bitterness in his voice, ‘I did not know then what lay within.’

‘Who made the new lock?’ I asked. ‘They could have made another key.’

Lord Parr shook his head. ‘You are right, it is an obvious point. But the Queen’s own coffer-maker constructed this lock, as well as all the other new locks. He is well trusted. He has been the locksmith to successive Queens for twelve years, and you do not keep a man in such a post if he is not trustworthy.’

‘Have you questioned him?’

‘Not yet. Again, I thought it best to leave that to you. But I do not consider him a likely suspect.’

‘Nonetheless, he is an obvious one.’

‘He works down at Baynard’s Castle. I thought perhaps on Monday you might go down there and question him. And talk to the embroiderer about that sleeve. Of course, they will not be there tomorrow, it being Sunday. That is a nuisance, but it will allow you a day of rest, and reflection.’

‘Thank you.’ I was grateful for the old man’s consideration. But then he continued, ‘What we really need is an expert on locks. Someone from outside the palace.’ He raised his eyebrows. ‘Your assistant Jack Barak is known to have experience in such matters. From the days when he was employed by Lord Cromwell.’

I drew a deep breath. So Lord Parr had been making enquiries about Barak. My assistant’s experience in such matters had indeed come in useful over the years, and yet – ‘I would rather not involve him,’ I said quietly.

‘It would help the Queen,’ Lord Parr pressed. ‘Barak need not know what this is about – in fact must not know. We will keep to the story of the jewel. But now the chest is empty I can send it down to Baynard’s Castle, and he can look at it when you are there on Monday.’

‘He would not claim to be a great expert – ’

Lord Parr looked at me hard. ‘He knows locks. And has experience of how the royal household works, the underside of it at least.’

I took a deep breath. ‘I will speak to him tomorrow, see what he says – ’