According to this on the BBC, the offer, in place since the New Year, has been taken up by hundreds of people.
Source: I was sent it a week or so back when CEO James Timpson unveiled the idea without much initial fanfair on Twitter. I tweeted about it as a great PR idea then, but since, it’s been picked up by mainstream media outlets including the Mirror, the Evening Standard and the Metro.
Thanks also to Tom Winterton at Citizen PR, who kindly thought of me when he spotted it, too).