‘My name is Peter Grant, I am a sworn constable of the crown and an heir to the forms and wisdoms of Sir Isaac Newton,’ I said. ‘I offer myself in exchange for the children, the mother and my friend. Take me – let everyone else go.’

She made me wait, didn’t she? Of course she did.

Then her smile grew wider and she inclined her head in gracious acceptance.

‘Dominic,’ I said.

‘You idiot,’ said Dominic.

‘Take the girls and Mrs Lacey and get out of here as fast as you can and go to the nearest place indoors where there’s lots of people – a pub will do,’ I said.

The Queen banged the butt of her spear against the ground.

‘I’ll be right with you,’ I said, and then to Dominic, ‘You’ve got to get a message to my governor, DCI Nightingale. Tell him that wherever they’re taking me it will be via Pyon Wood Camp, okay? The castle must be somewhere beyond that, in Wales I think.’

Two sharp raps with the haft of the spear – no more time.

‘They don’t like the Roman road,’ I said quickly, and handed Dominic my staff. ‘That would be a good place to intercept.’

Before Dominic could say anything I stepped forward until I was between Victoria and not-Nicole and the Queen. The unicorn I’d injured snorted and pawed the ground – I gave it the eye.

‘Now the girl,’ I said.

The Queen nodded cheerfully and set Nicole in motion towards her mother. She passed me, a small figure dressed in what looked like a woollen shift. I heard her mum sob with relief.

‘Dom?’ I called without looking round. ‘Have they cleared out of your way?’

‘Yes, they have,’ said Dominic.

‘Then off you go,’ I said and stepped forward.

You swear an oath when you become a police officer – you promise to serve the Queen in the office of constable with fairness, integrity and impartiality, and that you will cause the peace to be kept and preserved and prevent all offences against people and property. The very next day you start making the first of the many minor and messy compromises required to get the Job done. But sooner or later the Job walks up to you, pins you against the wall, looks you in the eye and asks you how far you’re willing to go to prevent all offences. Asks just what did your oath, your attestation, really mean to you?

I could have bottled it and not offered the swap. No disciplinary inquiry would have found me lacking in my duty had I merely sought to contain the situation and wait for back-up – in fact that would have been proper procedure.