It's very unlikely a British man would address another man, be he a fellow Briton or a tourist with such an affectionate term. The term used between men would be mate.
London taxi drivers (not private minicabs) used to be known for their cheerfulness and friendly banter, no longer true I'm afraid but if you do strike up a conversation you might be awarded with a love or darling if you're a woman, and mate if you're a man. The clichè term guv'nor which used to be a sign of respect, is virtually extinct in London.
Female strangers, if they seem friendly and /or need assistance will be addressed as love regardless of their age, and level of attractiveness. If a girl trips and falls while walking along the street, a Briton might well inquire "Are you alright, love?" It's a friendly but rather dated term as @DJClayworth pointed out. Conversely, if the same incident occurred inside a department store a polite shop assistant (thin on the ground these days) would probably ask:
Are you all right, madam/miss?
(An anonymous user added this to MariLouA's original post some months later: It should have been a comment. I hope MariLouA will accept it in the spirit intended. editor)
In Sheffield in Yorkshire in the 80s I was surprised as a man to be
called love by other men. In my native Liverpool , and now in
Manchester in Lancashire , this would have been very peculiar. It
shows the variation between places which are quite close together.
Sheffield and Manchester are only about 40 miles apart.