I'm currently listening to Britten's own recording. I wonder whether anyone listened to the Sunday Feature ? - "Phoenix Rising - The Story of Coventry Cathedral"
It is still available on listen again. I found it a fascinating listen - Britten finding the rehearsals and the acoustic not to his liking - "the idea was good" anecdote and a lovely sound clip of Britten exhorting the "dear hearts" in rehearsal to essentially get a grip :-) John Piper, Basil Spence (obviously ) are there too - a clanger that suggests the Cuban Missile Crisis happened before War Requiem was composed / performed - but also interestingly and movingly an exploration of how Coventry strives to maintain links to Berlin and Dresden to this day - to underline the importance and relevance to the present day of compassion and reconciliation. A very interesting interview with the precentor of the Cathedral - an Ulsterman - about how painful that process can be. Also I never knew that Tippett's King Priam was premiered in Coventry on May 29th 1962.
Here I hope is the link
http://www.bbc.co.uk/programmes/b006tnwp
I am looking forward to the performance tonight - although the 7 hour time difference between the UK and China means that I won't be listening until May 31st at the very least ;-)
Best wishes,
Tevot