Apologies if this has been posted before but I've just seen this book on Honest Toddler's Facebook page and it looks like a lovely way to talk to older children about St Nicholas and the origins of Santa.
I'm not sure whether my link to their FB page will work or not:
www.facebook.com/media/set/?set=ms.c.eJxFj9kVxDAIAzvaxyGu~%3BhtbB4LzOdYgQ2RAtJQ1vQq~%3BOMxpeThMatmSDFx5GSGUbpfbV1nmxxf6ePy3r7j987ZczX77efp8c~_952v1g078~_Jo8v73ns~%3B5DJxxei7j8nvyz65F5x~%3BZnf~_zD3sPwBBHs~_KA~-~-.bps.a.787418398054214.1073741829.185320894930637&type=3