So I finally remembered to check the Mk 4s at the hangar today.
Due to the location of the plate on the tubular, you can only see the entire plate when the right fuselage side panel is removed.
I could only see on 20304 (since it is currently being disassembled) that does indeed have the 'FW4-' prefix, but on all five of our Mk 4s the number following the prefix did not match up to the construction number.
That being said I'm pretty sure the Harvard (or T-6J

) you have is not CCF4-490.
The only way to know for certain what the true identity would be is to have the dataplate next to the throttle quadrant in the front cockpit.
And getting back to your original question I would still assume that it referrs to Fort William, but hopefully someone can find a definite answer.
Shane
