Their welcome bonus is worth around £18 on average. You put £5 into Coral and place one qualifying bet (costs roughly 25p). They give you 4 × £5 standard free bets, which we lock in on the exchange for guaranteed cash, plus 2 × £5 bet builder free bets that you place yourself. That average already blends the guaranteed cash with the typical value of the bet builders.

This is the first offer in the matched betting sequence, so you'll need to set up your Smarkets exchange account too. The money you put in isn't spent. It moves between your accounts to cover both sides of the bet, and comes back when you finish.

It takes about 35 minutes of actual work, spread over a couple of days. Once Coral's done, your exchange balance is boosted and ready for the next offer. Each offer after this gets that little bit quicker. I found the second one took half the time of the first.