Did post-war Hovis bread contain treacle or black strap molasses?

I totally concur with the opinion of YouTube chef Titli Nihan that the modern Hovis loaf tastes nothing like the bread I remember as a child. TN has an interesting theory that the Hovis bread of that generation was in fact based on white flour (rather than wholemeal), with the addition of black strap molasses and wheatgerm.

I seem to vaguely recall the latter ingredient being included from advertising, but the black strap molasses seems out of place. In that post-war world, the use of Tate and Lyle black treacle would seem more appropriate, especially as they had a major operational presence in the UK at that time. In her video, TN admits that her recipe isn't quite on point, could this be the reason, as black strap molasses and black treacle are not always interchangeable?

Reference recipe: https://youtu.be/Nu-v6ICAGKo