As far as I can work out, the problems with lining the Galway stem from its pattern and origins as a field boot.
It was (and still is, on the 64 last) a veldtschoen boot, the construction of which makes it, in its original form, one of the most 'waterproof' forms of leather shoemaking known. The boot has essentially two uppers, the lower upper being the whole-cut piece that is turned out and stitched down to the midsole, and the 'top' upper being welted underneath the stitched-down upper as normal.
Basically, the leg of the boot is part of that second upper and therefore also functions as the lining when you move down to the whole-cut 'outer' upper that forms the body of the boot. If you were to then actually line the leg, then you'd have three layers of leather around the heel of the boot. This would obviously cause some bulk, especially when the original versions of the boots would have been made of zug grain (like the one posted above) or the variations of country calf that I and others on here own.
To get the Galway lined, I think (and this is where someone more knowledgeable than me can chime in), you'd have to make some fundamental changes to the pattern, no? So would it still actually be a Galway as such?
With the shearling-lined Galways, the shearling itself only goes down as far as the outer upper, as I've tried to show here:
It's not just the EG veldt pattern that is similar - look at C&J's Snowdon, which is very similar and also unlined in the leg. I've just commissioned a special order Snowdon from C&J and they stipulated that the leg of the boot would have to be made of a sturdy leather, presumably so that it didn't just flop due to the lack of lining.
The earlier veldt boots by the legendary Lotus and later Tecnic and George Webb are all built like battleships, and never lined in their main patterns.
The only lined veldt boots I've seen have been Cheaney's versions like the Pennine, Fiennes and Mallory boots and also Alfred Sargent's Kelso and Selkirk models which they used to make before going all lah-dee-dah on us. All of these use or used a different pattern to the 'classic' field boot which can accommodate this and, as a result, look different in their own ways.
Does any of that make any sense?
It does make sense I knew there must be some reason why not to line it. However I have Galway on 82 last a Goodyear welted version and this one is unlined too. It is really not big deal as I will wear it with the thicker socks I was just curious about lining versus not lining reasoning.