Francois-Xavier Roth will substitute in London, where Boulez’s absence will be acutely felt during Daniel Barenboim’s Beethoven concerts, all of which are paired with works by Boulez. Here’s the press statement, just in:

BBC PROMS 2012
IMPORTANT CHANGES TO THE PUBLISHED GUIDE
13 July – 8 September
Since the BBC Proms Guide 2012 was published in April there have been some changes and additions to the advertised programmes. These are listed below.
Please refer to the Proms website (bbc.co.uk/proms) for complete, updated listings and contact a member of the BBC Proms press team if you need any further information.
Pierre Boulez
Due to recent eye surgery in the United States, Pierre Boulez is unfortunately unable to travel to the UK and will therefore not be able to conduct at the BBC Proms on 26 July or take part in the Proms Plus Intro event on 20 July. We are very grateful to François-Xavier Roth who will conduct Boulez’s Le marteau sans maître at Prom 17.
We are very pleased to announce that Daniel Barenboim will join Proms Director Roger Wright in conversation at the Proms Plus Intro event at the Royal College of Music, which will now take place at 18.15-18.45 on 20 July.
Prom 9 Proms Plus Intro (20th July)
Daniel Barenboim replaces Pierre Boulez in conversation with Roger Wright at the Proms Plus event, which will now take place at 18.15-18.45.
Prom 17 (26th July)
François-Xavier Roth replaces Pierre Boulez as conductor in Le marteau sans maître.

François-Xavier Roth conducting the BBC National Orchestra of Wales at the BBC Proms 2011.
© Chris Christodoulou/Lebrecht Music & Arts