'My people!' he cried in a loud voice. 'This is a day like no other in the long history of our race.'

He paused and I felt the air quicken around me with anticipation. The crowd, as a solitary creature, keen with yearning, held its breath.

'Rejoice!' the Emrys shouted suddenly, and I swear I heard his shout echoing across the surrounding hills like thunder.

'Rejoice!' he cried again, lifting his hands high. 'For this day begins the Kingdom of Summer, may it endure forever.

'Listen! Hear the words of the Chief Bard of Britain, Taliesin ap Elphin ap Gwyddno Garanhir: "There is a land shining with goodness where each man protects his brother's dignity as readily as his own, where war and want have ceased and all races live under the same law of love and honour. It is a land bright with truth, where a man's word is his pledge and falsehood is banished, where children sleep safely in their mothers' arms and never know fear or pain. It is a land where kings extend their hands in justice rather than reach for the sword; where mercy, kindness, and compassion flow like deep water, and men revere virtue, revere truth, revere beauty, above comfort, pleasure, or selfish gain – a land where peace reigns in the hearts of men; where faith blazes like a beacon from every hill, and love like a fire from every hearth; where the True God is worshipped and his ways acclaimed by all."

'Thus Taliesin spoke, bequeathing his bright vision to a world ruled by the Powers of Darkness. Today, it pleases the High King of Heaven to honour the words his servant uttered so long ago. People of Britain, hear me! Rejoice and be glad, the long-awaited day has dawned.'

The High King took his place beside Myrddin then. As I gazed upon Arthur, tall and strong, his handsome face lit by golden morning light, the white stone of the shrine fairly glowing behind him, I knew that the Wise Emrys, as ever, had spoken the truth. The High King drew his sword, Caledvwlch, and raised the naked blade like a cross and held it before him.

Today, in your hearing, Taliesin's prophecy is fulfilled,' he said. 'My friends, the Kingdom of Summer is begun. Taliesin's fair vision has become reality. Here we begin, and may the Living God crown our efforts with every virtue.'

Arthur lofted the blade-cross, and the host of people gave voice with a great cry of acclaim. 'Pendragon! Pendragon!' Their shout became a flood rolling down the hillside to spread throughout the land. 'Pendragon!' In that moment, the High King, bold and bright before them, became the long-awaited Summer Lord.

After a time, the cry died down, allowing Arthur to continue. Lowering the great sword, he placed the point of the blade against the stone at his feet, and folded his hands one over the other atop the pommel. Then, gazing out over the people and the valley beyond, as if into the far-distant future, he said, 'What is begun this day will burn in the hearts of all who hear of it. What is begun this day will be a boon of rich blessing to the people of every race and tribe.

'What is begun this day,' Arthur Pendragon said, his face shining in the morning light, 'will last to the end of the world, when God shall roll up the heavens like a parchment and return to Earth to reign in righteousness for all eternity. So be it!'

Delivering his sword to Myrddin, the king turned, stepped to where Avallach stood waiting, and, with a bow of acknowledgment to the Grail's first Guardian, placed his hand on the casket and opened the lid. The world was lit with a sudden flash of radiance – as if lightning had been shut up inside the box to be released at this moment. The onlookers gasped as Arthur reached in and withdrew the Grail and raised it high. I do not know what others saw, but I beheld a footed cup which glittered and shone in the bright sunlight as if it, too, were alive to the light that danced over and around it. A row of rubies and emeralds glittered around its foot, and the rim was set with pearls; a broad band of impossibly ornate scrollwork bent around the bowl, catching the light and throwing it off like sparks from a golden flame.

My heart soared as I filled my gaze with that rapturous sight. I felt myself grow stronger and, yes, more noble – as if the light revealed the man I was meant to be, but so rarely was. And I was not the only one to feel this way: from the murmurs of amazement around me, I guessed that all who beheld the Lord Christ's bowl were in that selfsame moment granted a vision of the Good God's redeeming grace.

It happened in the blink of an eye, the narrow space between one word and the next – for yet was Arthur speaking. 'Behold! I give you the Cup of Christ, which shall be the emblem of the Summer Realm, and a perpetual reminder of the source and sustainer of our good fortune.'

So saying, he stepped to the entrance of the shrine and placed the Grail on the altar stone which had been prepared for it. This done, he reverenced the cup with a bow and stepped away from the altar. Outside again, he retrieved his sword from Myrddin, raised it, and declared: 'From this day I have done with war and killing. Strife and violent contention have no place in the Kingdom of Summer. Henceforth shall Britain be called a land of peace.' Stepping into the shrine once more, he laid Caledvwlch before the Grail, point on the floor and hilt resting against the altar stone, so that the blade looked like Bishop Elfodd's cross. The High King then knelt before the altar and offered up a prayer.

Father in Heaven, never let me forget that sight: Arthur on his knees before the altar, his head back, face tilted upwards, his strong arms outspread, palms upwards to receive the blessing he sought. And above him, shining with the brightness of the sun itself, filling the shrine with a high and holy light, the Grail.

How long he remained in the shrine, I cannot say – for the moment was eternal and all creation held its breath. When he emerged, it was to a world subtly, but surely, changed. Arthur himself seemed fairer, stronger, more noble – as if all those lordly qualities which he already possessed in rare abundance had been expanded, increased, multiplied within him, and he now assumed a greater stature than before. If anyone doubted his own perception, he had only to look at Gwenhwyvar; the expression of admiration and love commingled in her eyes would have convinced the hardest sceptic that here before us stood a lord transfigured.

The High King, his face shining with the reflected glory of the Holy Cup, slowly raised his hands in a gesture of benevolence and said, 'May the Grail which we have established in this shrine serve as a beacon of hope to all mankind. Let it hereafter be said that once upon this Island of the Mighty, men and women loved virtue more than their lives, and sacrificed themselves to the rule of truth and justice.

'Friends,' he said, 'we have kindled a flame that will burn to the end of the world. We are men still, but God's own Cymbrogi stand in awe of the things we shall do. Even now angels are gathering to assist us on the journey we have begun. Signs and wonders will become commonplace, miracles will multiply in abundance, and peace will wash over the Island of the Mighty like a great sea wave lifted on the wings of the storm.

'I ask you, who can stop the waves? Who can tame the ocean's fury, or harness the sea's colossal strength? Who can bid the sun to halt in the sky, or stay the steady march of the seasons?

'I tell you the truth, we shall do all these things and more who pledge fealty to the Kingdom of Summer and its Eternal Lord. For if we remain loyal through all things, Britain will be the wonder of the world: a torch that is never quenched, a holy fire that cannot be extinguished. And all the nations that dwell in darkness will lift up their eyes and will behold the light of their salvation, burning as a beacon in the night. They will look up, and they will rejoice, and so great will be their rejoicing that the sound of celebration will overwhelm the sound of war. That hateful craft will pass away, never to be remembered.'