Christopher de Hamel is arguably the greatest living authority on medieval manuscripts. When he writes a book – even one this short – we should pay attention. He believes he’s solved the mystery of an early portable psalter sometimes said to have belonged to Thomas Becket, archbishop of Canterbury from 1162 to 1170. His discoveries, which resemble the pieces of a jigsaw, could hardly be better timed: 2020 is the 850th anniversary of Becket’s murder in Canterbury Cathedral by four of Henry II’s knights and the 800th of the removal of his bones from their first resting place in the cathedral crypt to an opulent new shrine behind the high altar.

What can we say about the psalter itself? Lacking its original cover and rebound in 1750, it dates from around 1000 and can be found in the Parker Library at Corpus Christi College, Cambridge, where it’s shelved not far from Becket’s own copy of his friend John of Salisbury’s Policraticus,