Why is the front brake lever on the right if you 'drive' on the left and vice-versa? I live in the UK and I expect my front brake lever to be operated by my right hand. However, I recently went on a friend's bike that had the brakes 'back to front', which would be the 'right way round' for people in Europe, North America and everywhere else that drives on the right.

I am left-handed and therefore used to finding things designed to be best operated with the right-hand, e.g. the controls on a lawnmower.

What are the reasons for the brake lever convention on a bicycle? It seems that the front brake is more important for controlled braking, in the UK we have that worked by the right hand, which makes sense. For countries that drive on the right that means the back brake has the 'handed-ness' advantage, rather than the front.

I also like to be controlling my speed with the front-brake when making a right-hand turn, however it is not possible to do this when signalling. A left turn is not so important to stick your arm out for - drivers coming the other way and behind don't really care if the sign is not made for a left-hand turn, whereas a right-hand turn really should be indicated. So, from that perspective, the brakes are the 'wrong-way-round' for me.

Can someone kindly guide me through why the brakes are wired up so and any historical origins of the convention?
I believe the reason is that the hand signals used to indicate braking generally involve using your 'road side' hand. In countries that drive on the left, this is your right hand and vice versa.

The back brake was considered the 'safer' brake to use during this pre-braking time when you're indicating that you will brake but haven't necessarily started braking yet.