These vehicles are, on the surface, acting quite legally.
However, this is a LOADING ONLY zone and the limit is 20 minutes (see the sign? "No waiting 7am to 7pm"). This is because it is an extremely busy stretch of road and, here, it is at its narrowest and only yards from a main junction with traffic lights.
Both vans were there on the way to Wandsworth and, 40 minutes later, still there on the way back. Incidentally, they were still there over an hour later on the return journey from Aldwich. And, as ususal, not a sign of any loading, nor (you will note) any traffic wardens.
Is this the "turn a blind eye" syndrome working again?