The point may be that the formulation underlying Kentmere 400 may not be an original Ilford/Harman formulation to begin with (see link provided by Anon Ymous), so may not fall under whatever Simon said.
Where did you got that?
Sorry to say that, but you got it wrong.
Kentmere 100 and 400 were introduced in 2009 first in the US market as a budget alternative to the more expensive Ilford films.
They are new emulsions from Ilford/Harman and are marketed as Kentmere and not Ilford just from a strategic and marketing point of vue.
See:
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