SEAT Leon FR petrol - Brake imbalance?? - non-stop

My Leon just celebrated its 3rd birthday with an MOT pass - but only just. Advisory note says 23% front brake imbalance and mechanic was surprised I hadn't noticed pull to one side. I have since tried normal, firm and emergency stops with no grip on the steering wheel and the car pulls up dead straight. Is there a system in the car compensating for the imbalance, or do I wait until next MOT/service?

SEAT Leon FR petrol - Brake imbalance?? - Collos25

There are two brake circuits on modern cars one front wheel and the diagonally opposed rear wheel so its not a straight forward as it seems.Brake imbalance can be caused by so many different things thats its almost immposible to diagnose without the car been checked thoroughly.

SEAT Leon FR petrol - Brake imbalance?? - bathtub tom

There's a geometry Vauxhall advertised years ago called 'offset steering geometry' that, I suspect, all manufacturers use.

The pivot point of the steering for the wheel is outside the centre line of the wheel thereby 'self steering' the car to the side with the least braking, thus effectively negating the effect of braking imbalance.