An Xmas Problem

I've spent a substantial amount of the day working on my regular Xmas quiz that appears in the Australasian Chess magazine (Note: I do receive remuneration for my work from the publisher). This year I was fortunate to pick up some new problem books in my travels, as normally I agonise for weeks over what I should put in there.
Indeed there was an almost embarrassment of riches and I was even able to leave some interesting problems out. The diagrammed position was one study that made the preliminary list, but was cut from the short list. Nonetheless for those who do not subscribe to Australasian Chess, you can put your mind to solving this one. It is White to play and draw, and was sufficiently difficult so that my copy of Fritz didn't spot the answer.