David makes a good point (pun not intended) about rail wearing - perhaps I should give the new S Scale Society code 87 rail a second thought!
Being utterly pedantic (wot, moi?!) Paul's deep ballast technique is OK for the period of his Dinas, but only until one gets to rail joints which were deliberately left exposed so that fishplates (Spooner & Huddart type) could be examined and maintained, and at points, as Richard remarked.