Mercedes designed for a primarily left-hand drive market, so the hand brake is positioned for the convenience of left-hand driving position. Many British cars, like my MGA and MGB, are designed for a primarily right-hand drive market, so the hand brake is positioned for the convenience of a right-hand driving position.
Gentlemen operating a left-hand drive M.G. or a right-hand drive Pagoda, when reaching across the transmission tunnel to operate the handbrake, may occasionally avail themselves of an opportunity to brush against m'lady's leg . . . ;^)