Depends on how many people are at the interview with you and how urgently you're needed.
Answered - Sales and Animal Care worker (Former Employee) - Bangor
I knew within 1 week.
Answered - Part Time Sales Assistant (Former Employee) - Salisbury
Again this depends but it can be the next day, they usually know who they want just takes time to get round to calling so don't be afraid to call up and check.
Answered - Colleague (Former Employee) - Hove
Was working experience
Answered - Store Assistant (Former Employee) - Gateshead, Tyne and Wear