Sainsbury’s has turned the Christmas task of testing the tree lights into part of its ad campaign this festive season.

Sainsbury's ad

Its ‘Will the Lights Work?’ adverts feature at bus stops and travel hubs across the UK and have built-in giant plugs that allows passersby to test whether the bulbs in the poster will glow when they flick the switch. As long as it doesn’t involve untangling the lights, the ads are likely to spark excitement.