yeah so two things to try, try emulating the MAC address (maybe called MAC cloning) of the BTHomeHub in the netgear's setup.
if that doesn't work, try going into the BTHomeHub's settings and look for something along the lines of, uh, setting it up as a bridge (can't remember the different terms they may use, essentially you're just telling the one router to act as a gateway to the netgear, which will handle the routing)
I'm not going to be of much more help, i can't find the setting in my own router to do this at the moment :/

god speed!