They must have looked odd together, the Frankish king and the courtier who later memorialised him. Charlemagne was tall for the period, around six foot three. Einhard meanwhile, his friend Walahfrid Strabo wrote, was ‘despicable in stature’ – a ‘tiny manlet’, in Einhard’s phrase.

Born into a family of modest wealth, Einhard was educated at the abbey of Fulda. We don’t know if he ever sought a monastic life, but he arrived at the imperial court in Aachen in the early 790s where, it was said, he buzzed around like a honey-laden bee. Einhard’s life of Charlemagne, the Vita Karoli Magni, wasn’t written until some 15 years after the king’s death in 814. Einhard himself lived on until 14 March 840.

His primary source, he said, was ‘the witness of my own eyes’; but the Vita is so derivative of Suetonius in both style and structure that some historians question its utility as a source. Even the physical descriptions of Charlemagne follow his model, drawing on at least six of Suetonius’ portraits of the emperors.

But one of Einhard’s aims was to place Charlemagne in the line of Roman greatness. That the Vita survives in 123 manuscript copies attests to his success. As for himself, he habitually signed his name ‘Einhardus peccator’, Einhard the sinner, never losing sight of his own insufficiency.