This brings back an embarrassing moment. I was trying to play some tunes from a children's religious chorus book, years out of practice, and needing to recognise a tune to get it right. I was in the school hall at lunch time, struggling away with these chords that hid the tune, and not having the slightest idea what it sounded like, just working out how to fit something like "Oh Praise the Lord, oh praise the Lord, oh praise the Lord for he is good" to it. And the Head master came up and asked me what on earth I was playing that for, told me that one of the dinner ladies was very offended and that I was never to play it again. My scheme to sing Oh Christmas Tree unfortunately never came off. I didn't have the guts!

Penny