Running a World Cup sweepstake is ILLEGAL
Have you done a World Cup sweepstake at work? Gutted that you landed New Zealand whilst that bloke who doesn't even like football from HR got Germany? It doesn't matter because you're all criminals.
The Gambling Act outlaws lotteries and unlicensed betting, but there are exceptions. If your sweep randomly allocates teams to people, then you're running an illegal lottery.
"The Gambling Act does not explain what is meant by a single set of premises, but Gambling Commission guidance indicates this was intended for the situation where there are multiple buildings on a single site, and that it is not meant to cover multiple sites," said Susan Biddle via The Reg. "So if you have premises on more than one site, you would not be able to run a single sweepstake across more than one of your sites."
The law says that tickets must be in the form of a document and state: the name and address of the promoter; the group of people who are eligible to buy tickets; that the ticket (and the right to any winnings) is not transferrable; and the price of the ticket.
The exemption also only applies if no profits are made from the sweep and 100% of funds are paid out as prizes.
If you're weird and choose your teams as a prediction for who'll win, then this competition would be classed as 'betting' under the Gambling Act. To fall within this exception the betting must take place between people who are all employed by the same employer.
So. Susan Biddle is on hand.... but worry not because:
a) She's produced a free guidance on the issue to enable you to avoid legal bother, which you can read here.
b) Like anyone gives a shit anyway. A World Cup sweepstake is little more than an adult version of coiny. The police aren't going to raid your office and club you to death or anything (unless you live in London. I wouldn't put anything past The Met).