Also double check your wheel bearings, mine used to randomly pull hard to the left when braking, but only for a second, and sometimes it would be fine. Ended up being the RH wheel bearings were stuffed, and as far as I could tell it was because the LH caliper would grab fine but the RH would be out of action until it managed to readjust itself, or something like that, it was odd and nearly got me into trouble so I'm glad I sorted it.
I've also had similar problems, like real bad torque steer, because one of the steering arm bolts had sheered off
): British Open Classic has 12'' rims with discs on the front. 
] Man she must stop on a dime with all that 8.4 inch braking power....what size wheels are you running 12 inchers 