I believe the correct route was taken regarding the National Gallery House. Just because the shopfront was lost/had to be replaced did not mean the entire house had to be altered accordingly. That would be extreme, unnecessary, and wasteful of both money and extensive historic fabric. If the Victorian alterations had been less all-pervading, a better case could be made.
Graham: I would have knocked off that Victorian icing sugar fringe myself with a lump hammer, if cost was the issue.
It may be just a personal thing, but these Georgian houses, including your example from Dundalk, depend so heavily on the proportions of their window fenestration for their aesthetic appeal, that not to reinstate their glazing bars just seem like a slap in the face to the original designer, IMO.
I don't think that we need to grant equal respect to everyone who's had a go at any given building over a couple of centuries. In my opinion, the first intention, the original design, should have an assumption of primacy in any hierarchical evaluation of the conservation priorities. No. 10 Mill St. (as we've discussed before), a definite case in point.
I believe that the opposite position (which seems, to me, to be the current dominant position), where the various accretions demand as much respect as the original design, is just plain wrong.
There are obvious exceptions like the Rubricks block in Trinity, where the Victorian additions added a whole level of interest and scale that wasn't really there before, but usually alterations (often by the Victorians) were pretty shallow and usually took away
more than they added
to the character of the building they altered.
There's probably an Archiseek thread on conservation that it might be better to continue this discussion on.
On the National Gallery house. I'm going to wait until I find a pre-renovation photograph before I shoot my mouth off any more about this. My gut feeling is, that the Victorian shopfront, the window replacement and the frilly trim, were (or appeared to be) a package deal, and it might have been better to retain this version of the house, or put the clock back to the Georgian original, in full, rather than do a bit of both.
We'll dig out a photograph and take it from there.