That set is probably correctly numbered, Paul, because it has two standard coaches the 71XXs and a restaurant which should correctly have a 74XX number. The coach in Wrenn's photos is a STANDARD coach , not a restaurant, but incorrectly has been numbered 7411 (which should be reserved for a restaurant coach). It seems that some of the standard may have been misnumbered, probably not too many as few people are aware of it.
WT, things have certainly slipped lately, but you also raise a good point as these should probably be numbered 72XX as neither is designated as a first class or composite on the doors