I have accidently performed this mating in the past and then experimented a little with the progeny.
This bird is the product of a GLW X LS
Notice the light edging across the back just behind the hackle. The bird hatched with Co wheaten style down. The black edging was less noticeable a few months after this photo, but became stronger after the second adult moult.
This bird was mated back to GLW and did not produce a single offspring with lacing that I thought was worth continuing with, although the crescent edge was present in many of them. I never counted and recorded numbers of phenotypes that were produced, but none had eb down at hatch and none had Co eb type down. All second generation still appeared a variance of wheaten down but I did not photograph them and I am working for 7yr old memories.
My second 'experiment' was the reverse mating LS x GLW and produced the following :-
black crescents are clearly visible over the back area, as is dark underdown, although these birds did not have as dark underdown as a pure Co Wyandotte. The ckls from this mating had black stripes in the saddle hackle. The dark underdown and saddle markings in the ckls is why I viewed the eb gene as dominant to the eWh, although I discounted the fact that these birds all hatched with Co Wheaten down pattern.
These hens were mated back to a Columbian Wyandotte Roo. Down colour in these chicks was evenly spread between Co eb and Co eWh patterns. All birds produced were typical columbian pattern. One quarter (roughly) should have been eb/eb, Co/Co, Ml-Pg/+ but none of them had greater lacing or crescents than the F1 generation.
Now what is even more interesting is the outcome of another 'experiment' I have in my yard at present, but I do not have a photo as yet. Its what happens when a Wheaten bred Blackred Modern Game flies the fence into your pen of large hens just prior to the breeding season. Somehow he managed to serve a Large GLW hen. One chick was produced which I did not distinguish as different from the other wyandottes at hatch. But the bird now has extensive markings exactly the same as Smyth reported for Ml-Pg/+. This bird is also definitely eb/eWh. The only difference to those produced from the LS matings is that it is Co/+ instead of Co/Co.
Therefore I suspect that the birds in Smyth's diagrams were also heterozygous for Co and that is the critical difference