Caudalie, the French vinotherapie skincare house, runs a product-testing page on its UK site inviting people to try a bestseller and feed back on it.

The page asks you to “answer our 5 questions so we can get to know your skin’s needs”, then matches you to a travel-size product from its range – most recently the Premier Cru anti-ageing line – and posts it out to you to test at home.

There is no purchase requirement for the test itself; you simply register your skin profile and contact details on uk.caudalie.com. Numbers are limited, so it is worth applying promptly.