If you walked away with the top prize in the Grand National office sweepstake you’re probably pretty pleased with yourself, but did you know you may have broken the law just by taking part?

Millions of workers in serviced offices London city and further afield had a flutter on the race at Aintree over the weekend, but they may have inadvertently been going against rules set out in the Gambling Act of 2005, according to Kirwan’s Solicitors, which spoke to About My Area.

Sweepstakes of this sort fall under the definition of a lottery, which companies cannot legally carry out without a licence.

Even if proceeds go charity, it is still unlawful. It is only if all the money is distributed between the winners that the sweepstake can fall inside the law.

James Corlett, a commercial solicitor with Kirwans, said: “Grand National sweepstakes may seem like a bit of harmless fun, but the reality is that unless they are carefully organised, there is a distinct possibility that a business could find itself in hot water.”

The Grand National took place on Saturday. A horse named Ballabriggs came first in the race, with Oscar Time second, and favourite Don’t Push It taking third prize.