First, they will struggle to cross London due to transport clusterf***s; by the time they arrive you might have sobered up. Second, you want straightforward pleasure — you don’t want to wake up from your post-coital reverie on a mild Monday and realise you have “ex stuff” to untangle. And third, you can do better than that. Use a location-based dating app to find someone nearby, or walk around the communal hallway half-dressed until your hot neighbour comes home and needs warming up.