Oliver Cromwell's Head - The Most Talked About Head in History?

I was listening to a set of lecture on British history and came across the most fascinating little nugget on Oliver Cromwell's head. Cromwell, who presided over the temporary transformation of England from a monarchy into a republic in the 17th century, seems to have somehow had his head misplaced. It wandered for almost 300 years before finding a permanent home.

What's really fascinating about all this is how a head could go around for so long and not be replaced by a plethora of fakes. I mean really, how hard would it be to fake a Cromwell head after three hundred years? Also, how did the value of Cromwell's head almost double in 12 years? I bet there are some investment bankers out there who wouldn't mind investing in Cromwell heads for that kind of return. Too bad there's only one.