Michael Richardson asked if I could identify this coin for him. It’s a voided short cross penny, which is a type first introduced during the reign of Henry II and it continued to be issued well into the reign of Henry III.
On the obverse of Michael’s find is a large head with a full beard made up of chin and cheek whiskers. The distinctive head marks out this penny as a coin of class 3 of Richard I. On the reverse the legend reads +REINAVD ON CA, so Reinavd is the moneyer and Canterbury the mint.
The obverse would grade about VF for the issue but there is damage to the edge by the last four letters of HENRICVS; the reverse isn’t as sharp as the obverse. On the plus side, voided short cross pennies of class 3 of Richard I turn up much less frequently than those of class IV.