B is mis-stated in this article (and therefore in your summary): it's about whether the type of work is part of the type of business, not about the location. The decision gives an explicit counterexample that a plumber fixing a bathroom in a retail store does not fail test B and still counts as an independent contractor, because even though the plumber is on aite, the retail store isn't engaged in plumbing work.

(B would be a surprising change for consultants and trainers if it were about location, but it seems to avoid that.)