Thanks Mamyalynne. I've submitted Mark Williams as my answer. There is usually more than one answer that will fit - they keep adding more letters on a daily basis until someone guesses correctly. Mark Williams is a good a guess as any. I'll let you know the correct answer soon. I think you deserve 'best answer' whether it's right or wrong, Mamyalynne.
Yes, it's very hit and miss, Mamyalynne. Suranne Jones was right, Scorpio - thank you. I've made myself a note to come back here with the correct answer as soon as I know it.
and the answer was.... Mark Williams, although I wasn't quick enough to win. I'm stuck on today's. It's proving to be a bit of a silly game. I'll post a new question.