Hmm... I'm a little shocked that during your MOT test the inspector would even look into stuff that was not originally fitted. I suppose one option would be to use something like a 951 system that is self contained and just not hook up the warning lamp. Then theere is no lamp to fail inspection. Besides, I've never understood the virtue of having the ABS lamp come on when you brake hard enough activate the system anyway. If that's the case you're probably not looking at the dashboard, and you can feel the system working anyway.