He looked at me sharply. ‘Of the Queen’s?’

‘Yes. She had a new lock fitted in the spring, the other one was – old.’

He bent and peered closely at the lock, inside and out. Then he said, ‘I’d better see the key. I saw Lord Parr give it to you.’

‘Don’t miss much, do you?’

‘Wouldn’t still be here if I did.’

I handed him the key. I wished he had not asked about the Queen. But if I limited his involvement to the chest, surely he would be safe. He studied the key’s complicated teeth closely, then inserted it in the lock, opening and shutting the chest twice, very carefully. Finally he took a thin metal instrument from his purse and inserted it in the lock, twisting it to and fro, bending close to listen to the sounds it made. Finally he stood up.

‘I’m not the greatest expert in England,’ Barak said, ‘but I would swear this lock has only ever been opened with a key. If someone had tried to break in using an instrument like mine, I doubt they’d have succeeded – the lock’s stronger than it looks – and I’d expect marks, scratches.’

‘The Queen says she kept this key always round her neck. So no one would have had the chance to make an impression in wax to construct another. I think there must be another key.’

‘And the only person who could have made that is the locksmith, isn’t it?’ Barak said, raising his eyebrows.

‘So it seems.’

He rubbed his hands, his old enthusiasm for the chase clearly visible. ‘Well, let’s go and see him.’ He smiled at the guard, who looked back at us impassively.

THE CARPENTER’S WORKSHOP was at the rear of the hall, a large, well-equipped room smelling of resin and sawdust. A short, powerfully built man with regular features only half-visible through a luxurious growth of reddish hair and beard was sawing a plank, while his young apprentice – like his master, wearing a white apron emblazoned with the Queen’s badge – was planing another piece of wood at an adjacent table. They stopped working and bowed as we entered. At the back of the workshop I noticed a set of locksmith’s tools on a bench.

‘Master Barwic?’ I asked.

‘I am.’ He looked a little apprehensive, I thought, at the sight of my lawyer’s robe with its own Queen’s badge. But then he would know of the theft, and that he might be under suspicion.

‘I am Matthew Shardlake, Serjeant at Law. I am enquiring for Lord Parr into the loss of a jewel belonging to the Queen, which she values greatly.’ I turned to the apprentice, who was small and thin, a complete contrast to poor Elias. ‘Does this boy help you with lock-making?’

‘No, sir.’ He gave the boy an unfavourable look. ‘I have enough trouble training him up on the carpentry side.’