Several of the locomotives have been done, well there larger scale counterparts have been, could easily be rescaled using Shape File Manager.(3) Fairbourne route and stock (12.25 inch)
Would be nice, but there is already a good model of the Garratts available, and with no realistic route to run them on, really isn't a great deal of requirement.(4) An Updated model of Garratt No138 and a model of Garratt No87
Have been made, but never released. Again as the above, with no route to run them on, very little need for them.(5) The NG15's from the Welsh Highland railway
Ben