Allan is the BBC correspondent in Rome and reporting from the Vatican. Unfortunately he is simply unable to get back in time for this event. His lecture will be delivered by his wife and fellow broadcaster Sheena McDonald, who met him while he was living in Sarajevo and also spent time with him during the Bosnian War.

We and Allan apologise for this change but believe that Sheena is the best possible stand-in for him.

If you have already purchased tickets for this event and no longer wish to attend, please present your ticket at the main Box Office in the Visitor Centre to exchange your tickets for another event or a refund.