‘Tush, Sir John, patience,’ Athelstan replied. ‘Let me work it into a pattern. Let me get the proper sequence of events, then I shall tell you what I know and the problem will be resolved. But for now you stay here, examine the indenture, reflect on what you have said. I won’t be long!’

Before a bemused Cranston could reply, Athelstan had slipped out of the room, walking gingerly across the noisy Nightingale Gallery, down the stairs and out into Cheapside. Just in case he met any of the Springall household he went down Friday Street, turning into Bread Street and back up St Mary Le Bow. The church was open. Athelstan went into the nave and sat at the base of a pillar, legs crossed, whilst he stared up at the high altar behind the rood screen. He looked round the cool, beautiful church, at the frescoes on the wall, lectern, and pulpit of exquisitely carved oak. From the stalls in the sanctuary he heard the master assembling the choir, rehearsing the hymns and canticles for the feast of Corpus Christi. Athelstan leaned back, letting his head rest against the coldness of the pillar whilst he stared into the darkness, trying to rearrange what he knew, to make the pattern complete and trap the murderer. This was one occasion when the sons of Cain, the killers, would not turn round and claim with mocking innocence, ‘Are we our brother’s keepers? We are not responsible because we are innocent,’ while the blood of five human beings stained their hands and darkened their souls.

The choir began the beautiful hymn ‘Pange Lingua’. Athelstan let his mind and soul be calmed, moved by the rhythmical chanting. At one point the youngest boys, the choir’s sopranos, took up the refrain, pure and lucid, filling the entire church with angelic sound.

‘Respice. Respice Domine. Look back, oh Lord, look back on us!

Athelstan muttered the words under his breath. ‘Look back, oh Lord,’ he prayed. ‘Give me wisdom and light. Let me plumb the darkness, root out the wickedness. Let those things that were done in the dark of night be revealed for your justice and that of the king in the full light of day.’

Athelstan meditated for an hour. He saw the irony that here he was in a church, the house of God and gate to heaven, thinking about murder. But gradually the pattern was resolved. The culprits were identified, their motives revealed, and he reluctantly admired their deviousness, the sheer wickedness of their plan. He built his own traps, hedging them about, and, when he was ready, returned to the Springall house.