Out of interest, Mlb3c, here a licence is required to sell liquor and intoxicating beverages.
There are 2 licences required though.
The premises must be licensed, and the person named as the premises supervisor, on the premises licence, must also hold a personal licence.
A premises licence details exactly what licensable activities are allowed to take place, at what hours. For example, alcohol sales between 0600 and 2300 hours (with a premises supervisor). For a casino it might be gambling at any hour. A premises licence is also required for late night refreshment provision - this is the sale of prepared food after 11pm.
In the event of an illegal sale by anyone in that store (whom there is written evidence that the premises supervisor has given permission to sell alcohol), the following can happen.
1. seller recieves large fine (max £5000 though normally £80 fixed on the spot)
2. premises supervisor recieves large fine / prison sentence
3. supervisor's personal licence revoked (most stores have 2 or more with a personal, so they can take over should this happen)
4. premises licence revoked
5. restrictions placed upon the premises licence, or a temporary revokation - normally 48 or 72 hours.
The authorities can impose any or all of the above penalties. I have seen staff dismissed from our company for selling to underage testers. Its not pretty. She failed twice so was dismissed.
Licences are not required to sell tobacco (as far as I know)