This attitude stirred unfortunate echoes of Wiltshire’s sour view of the force he had abandoned in the Welsh March and I sent up a silent prayer to St Michael that I had not drawn a short military straw again. ‘Perhaps they realize you have marched them all across North Wales for no good reason. Why did you not make landfall at Harlech as planned, duke?’ I gave him his title but not the deference that should have gone with it.

He scowled and his lip curled in a snarl. ‘I had business in Mostyn that is not any business of yours.’ He turned his back and surveyed the wild, brown landscape. ‘And what a dump we have marched into. This country is Hades without the warmth.’

I ignored his attempt to avoid my question. ‘It is my business, sir, since our plan was to attack Caernarfon Castle and your delay has given the Yorkist Constable time to strengthen his garrison and unmask the man I had planted inside to open the gates to us. A week ago he was thrown from the battlements with a noose around his neck.’

‘You did not choose a very skilful agent then, did you?’ With a shrug Exeter turned to his squire, a youth with the misfortune to have buckteeth. ‘Bring out the wineskin coney-face. I could drain a cask and our host does not appear to be offering any refreshment.’

Everything I had heard of Exeter’s unpleasant character had surfaced in the last few minutes but I swallowed the indignant riposte that was on the tip of my tongue and turned to Evan with a wink the foxy duke could not see.

‘Fetch his grace a draught of our best Welsh ale, Evan. That will quench his thirst better than wine.’

It was no surprise when the duke spat out his first gulp and emptied the rest on the ground. ‘Ugh – water! A man can die from drinking that.’

I shook my head. ‘No, my lord duke, not here in the Welsh mountains, unless your men have already peed in our stream.’

‘Well you are right there for once, Pembroke. Their Flemish piss would poison a man in seconds.’ Exeter grabbed the wineskin off his squire and tipped it high to suck a long draught.

I watched with distaste, summoning my patience with difficulty. ‘Nevertheless we need them if we are to have any hope of getting into Caernarfon Castle, so I advise you to order them to drink their fill upstream, urinate downstream and then march straight back down the hill to the coast in hope that we get there before William Herbert does.’