Wild Service Tree and hill-forts

Any suggestions please as to the identity of the `mine` on the Sorbus torminalis leaf below?
It was collected from a planted tree near Stradey Castle, Llanelli - I was given this tree by the late Ian Watt of Llandeilo and I, in turn, gave it to the late Sir David Mansel Lewis in c 1987. True wild trees also grow on the Stradey Estate, at the edge of a hill-fort in the wooded gorge cSW of Cencoed-uchaf farm, where I discovered them in 1974. Our local Carmarthenshire trees (at Cencoed-uchaf and elsewhere) have slightly more rounded leaves than the one from the planted tree shown below.
Incidentally, an old English name for the edible fruit (which you have to `bletch` or ripen like pears before eating) is `chequers`; hence the name to the PM`s country retreat.

Yesterday, went to another hill-fort - the huge Iron Age hill-fort at Garn Goch, overlooking the Tywi Valley near Bethlehem . Did not find anything moth-wise (though I`m sure that Sam`s skills would have turned something up!), but the area looks really promising for a spring/early summer visit in terms of diurnal moths. Doubtless good too for birds such as yellowhammer, linnet, cuckoo. Great habitat, easy parking, ideal for a picnic - and fabulous views.
Also it is right next door to Crug-las acidic pasture/mire SSSI (access permission must be obtained for the latter area from very friendly landowners). A poor photo (due to haze and -more so- my photography) is shown of just part of the `open access` Garn Goch below.

and another photo....