Don't you find it peculiar that Henman, a player who came up through the LTA British system and would have had access to the best coaches in the country, on several occasions has emphasized he uses a semi-western grip, even correcting someone who described his grip as eastern? I think Henman understands his game better than Yandall or Jeff whoever. Maybe, as you say, it's just different terminology for the same grip, but Henman clearly refers to his as semi-western, so if I'm uniformed, he must be too.
The coach in the first video I posted identifies the same problem I refer to in this thread, so I'm not the only one who has this view and this issue is clearly out there, as evidenced by the other poster here who shared his experience.
Anyone can just reel of tennis federations and say they support one's own position, look: These federations support my position, not yours, so are you saying they are wrong? See, it's easy.
You also do realize that Henman does not directly always answers the questions he receives on his website right?