A self-styled ‘grammar vigilante’ has revealed that he has spent years changing offending shop signs in the dead of night.

Wielding an ‘apostrophiser’ – a broom handle laden with two sponges and a number of stickers – the man has corrected tens of missing and misplaced apostrophes on shop banners across Bristol over the past 13 years.

The pedant, who is yet to reveal his identity, claims his efforts are needed to bring an end to the improper use of English. But critics suggest he should start with his own name – as apostrophes are strictly a matter of punctuation rather than grammar.