Common in the youth's of London and spreading across the United Kingdom rapidly. Allow is like a default word for 'fuck' or 'screw'. Aimed at either an inanimate object or particular person/group of people.
person 1: The boy's can't come to the cinema, they're watching the football.
person 2: Allow them. We'll go anyway.
Person 1: I heard him say that about you.
Person 2: Allow him, he's got a big nose anyway.
Person 1: It's going to be raining all weekend.
Person 2: Allow it. We'll go to the beach next weekend.
To Allow: specifically of females, to have sex
with. Usually only used in the conditional
, as in "I would allow that". Often abbreviated to "'low".
Steve: That bint is fucking dull, mate.
Dave: Yeah. You know you'd allow her though.
Steve: Fair enough mate. I'd allow.