If i recall correctly, i dont think TAGB is a ITF orgnisation, its seperate and is just the U.K's regulatory body. I could be entirely wrong as i havent looked into it that much and finding info about who is affilitated to who is difficult, but treating it as its own body is the best way to go. Isnt the ATA, in a similar sort of thing?
TAGB may draw more from ITF than WTF though. (and yes it will always be WTF to me)
If sine wave is what i think it is, it wasnt phased out of the place i went to (not TAGB, but a legitimate ITF offshoot) If its that weird crouching sort of thing black belts are taught to do.