It’s just a little over 400 years since the death of one of England’s greatest composers, William Byrd (1623). Cambridge Early Music’s latest concert, an engrossing survey of his music and poetry with the distinguished Chelys Consort of Viols and celebrated mezzo-soprano Helen Charlston, had the audience of St Catherine’s College chapel on Saturday evening completely enthralled. Byrd as a Catholic convert, like many of his recusant contemporaries, occupied the uneasy world of the Protestant Elizabeth 1, courting her favour yet being in constant danger of the terrible consequences of losing it….