They have been credited with putting the UK on the road to recovery, but the issue of zero-hours contracts is among the most divisive of the general election. People working under such an arrangement are contracted to work for an employer, but they have no minimum guaranteed hours.

Advocates say zero-hours contracts allow greater flexibility to employers and workers, create jobs and boost growth. Critics see them simply as a way for companies to drive down labour costs, leading to uncertainty and inequality among workers.

The Conservative-led coalition is largely supportive, pointing to the positive effects they have had on the economy. However, they have conceded there is a lack of clarity on workers’ status and have launched a review.

The main opposition Labour party has promised to clamp down on the worst excesses of zero-hours contracts. In a campaign promise the party said it would give employees the right to have a regular contract after 12 weeks of working regular hour