It’s a phrase that has become a mantra for personal injury and small claims lawyers. Imported from the US legal system in the mid-90s, No Win, No Fee is the consumer-friendly name given to a method of claims financing officially known as a conditional fee agreement.
It more or less works as the two names suggest - payment is conditional on the case being won. This means litigants don’t have to raise funds up front for expensive legal action, it is the lawyers that take on the risk, and final payment is usually taken as a percentage of the compensation won.