Ah now, how you can find your own tent is a really good question - specially in the dark after a boozy night. Its a purely random process. The rule is: If there's somebody already in the tent then its probably not yours.
Or the occupant is also in the wrong tent which may or may not be yours either. Are you sure you're on the right campsite anyway?
And do you have a vague memory about booking into a B&B earlier on in the day when finding your tent at night and after a boozy session seemed like it would be an impossible task.