In order to take Blackstone on this particular journey through France and into Spain I compressed some of the time it took for historical events to unfold. Don Pedro had set up his headquarters at Burgos with the expectation that his enemies would strike from Saragossa. He was mistaken and was outflanked. The mercenaries attacked from the south-east, sweeping north through the valley of the River Ebro. The campaign against him was rapidly executed by, among others, Sir Hugh Calveley, who had agreed to fight with the Breton Bertrand du Guesclin on the condition Hugh would not fight against the English Crown. He was well rewarded for his success and given the title of Count of Carrión. Needless to say, the Jewish and Muslim communities abandoned by Don Pedro in Burgos and other Castilian cities soon had their property seized. Don Pedro’s fate became ever more desperate and he ordered his treasury to be loaded onto a galley on the River Guadalquivir with orders for the ship to sail to a Portuguese port on the Atlantic coast. Gil Boccanegra, the Genoese Admiral of the Castilian Fleet, saw where his future lay and handed Don Pedro’s treasury to the enemy. King Don Pedro I was now all but defeated and he had no choice but to escape and plan a return to Castile with the help of the Prince of Wales and Aquitaine.

The underground tunnels beneath Burgos Castle are 62 metres deep and the well is an impressive testament to the skill of medieval stonemasons. The spiral staircase descends around the well’s walls to predetermined levels and then forms a passage to the opposite side of the well where the spiral staircase continues but in the opposite direction. This means those who used the staircase to reach the tunnels below don’t have to descend in the same direction all the way down.

I am always appreciative of the help I receive from readers who have specialist knowledge and patiently listen to my queries so I can attempt to get historical elements as accurate as possible. I am grateful to Chris Verwijmeren in Holland, expert in medieval archery, for his help with advising me about the use of Saracen bows and for his videos of how the Moors’ mounted archers balanced their swords on their bow arm ready for use. I also found the out-of-print book Saracen Archery by J. D. Latham, MA, DPhil (Oxon) & Lt Cdr W. F. Paterson, RN of great interest and help in my understanding of the skills of the Moors.

The steady hand of my ever-patient editor, Richenda Todd, guided this latest novel through the editing process, along with her usual keen eye and incisive comments.