Scott_D,
google
www.british-history.ac.uk/map.aspx - displays British History On Line
click on Ordnance Survey 1:10,560
click on Glamorganshire (51)
click on the square that includes the bulk of the word Bridgend
look closely at the top right hand corner of the map that appears and make out the word Llanharry (rather faint unfortunately)
position the cursor about 1/4 inch/5 mil below the first A in Llanharry and click
you should see TY ISAF on the screen (to the left of "Acres 1628.998).
Looks like a farm.
regards