At very short notice I had to pull out of my intended appearance at the Wrexham Carnival of Words. This was disappointing to the organisers, and deeply embarrassing to myself, especially because the reason for my cancellation was a mistake of my own making. When entering dates into my appointment diary (and more than likely when transcribing last year's diary to this one) I marked Wrexham down for the wrong date (27 instead of 22), and inadvertently double-booked myself on the correct day, when I was also due to be in London for an event organised with ESA. Unfortunately my error did not come to light until very close to the event itself. I am terribly sorry for this mistake, both for the aggravation caused to the festival organisers, and the disappointment to anyone who may have been intending to see me. Nothing like this has happened in all the years that I've been doing public appearances, and I sincerely hope it remains a one-off. Once again I offer my sincere apologies.