Head to any Boots which has a Benefit counter and you can trade in an old eyeliner for a sample of their new liquid one.
I popped out yesterday lunchtime and found there was plenty of stock left. It’s quite small, but it’s free so you can’t complain!
The deal ends on 11th September or when stock runs out. You can take any old eyeliner, even an empty one, whatever the brand.
You can find a list of stores with Benefit counters on Boots.com