There's a temptation, when learning a new song, to think that you know it when, actually, it's not yet fully embedded in your brain! I always write the song out by hand, in my song notebook, and I find that the act of writing it helps me to remember it later. I visualise the words on the page as I wrote them - not quite a photographic memory, I hasten to add, but a big help.

However, I rarely perform a new song in public until I've sung it out loud in practice for several weeks, sometimes months. I sing it in the car while driving, mentally run through it in my head whenever I can and then, and only then, will I perform it in public. Touch wood, I haven't stumbled over a new song yet by preparing in this way.

But, yes, we've all experienced sudden memory loss over things we've known for ages! I was introducing some colleagues to a visitor the other day - and couldn't recall the name of someone I'd known for 20+ years!