Quatrefoil key

[sparkyskey]

We purchased this lovely key just under a year ago on Ebay and ended up paying quite a bit of money for it - but we were still very happy with our item. As yet we have not seen another like it - some of the features appear on other keys - but never all on the same one. The key measures 5.5 cm (2.25 inches approx) and looks to have been cleaned at some stage (not by us). There is some pitting damage but this does not affect the attractively worked parts of the bow, shaft or bit. The "end on" shot shows the hollow shaft in a quatrefoil pattern. Our guess is that it was for a jewellery box or fine bureau? If anyone can tell us any more info we'd appreciate it.