John Stow claimed to have seen it, and said the king's head (with red hair) was removed by a glazier and eventually buried at St Michael Wood Street.It seems like anyone who was anyone in British royalty during this period had red hair. I guess it also opens the door to the idea that James V and other Stuart royals were redheads. Especially given that the wife of James IV was Margaret Tudor - whose mother was the red-haired Elizabeth of York, and grandmother the equally red-haired Elizabeth Woodville.
Incidentally, I also found out today that the famed Scottish king Macbeth was known as "the Red King". There doesn't seem to be any indication of what this "red" alludes to, but I guess hair colour could be an option. According to Wiki a verse history titled the Prophecy of Berchán states this about a ruler referred to as "the generous king of Fortriu" - thought by scholars to be Macbeth;
The red, tall, golden-haired one, he will be pleasant to me among them; Scotland will be brimful west and east during the reign of the furious red one.I haven't read Shakespeare's Macbeth since childhood, but I think I'll have to give it another whirl now :)