The following day Owen and I left for Carmarthen, where we had arranged to muster our siege army for Denbigh. He was as keen as I was to regain control of this particular castle and town, not only to fulfil our royal commission to do so but because Myfanwy wanted to return there.

As far as I was concerned Denbigh was a Yorkist lair and I had for too long neglected my duty to bring it back under crown control. The name meant ‘rocky fortress’ in Welsh and it certainly lived up to it. The castle was perched high on a prominence and surrounded by the town, which made attacking its walls practically impossible, even with the guns I had managed to acquire from the Tower of London. I was relying on my father to use contacts acquired during his sojourn there to winkle out informants who might enable us to enter the castle by subterfuge and I was not disappointed. In his absence York’s local support was declining and towards the end of May we managed to get the gates opened to us and install a new deputy constable with a substantial garrison loyal to the king.

However, jubilation at our achievement was short-lived. When we rode to Kenilworth to report to King Henry we discovered the royal family and their army had departed suddenly to confront a Yorkist invasion from Calais led by Warwick, Salisbury and York’s eighteen-year-old son Edward, Earl of March. First they seized and garrisoned the port of Sandwich; then, after recruiting substantial support in Kent, they moved on to a rousing welcome in London. We rode south to find that the royal army had dug defensive ditches on the banks of the River Nene at Northampton and were lying in wait for the invaders to make a move. A battle was inevitable. Meanwhile the queen and the prince had taken up residence at Northampton Castle with the constable, Duke Humphrey of Buckingham, but the king had taken refuge with the nuns of Delapré Abbey and, as usual was ‘not to be disturbed’.

‘Take your men back to Pembroke, Jasper,’ Buckingham ordered with his usual gruff authority. ‘Lord Grey of Ruthin brought a force from North Wales to join us a few days ago and we need you to keep watch on Herbert in the south. We do not want him creeping up on us without being confronted. The king will be delighted with your news about Denbigh and I will keep you informed of developments here. We will have no trouble trouncing these rebel Yorkists and if any survive the battle I have no doubt the rebel earls will soon be awaiting their trial for treason in the Tower.’