Wikipedia's grammar vigilante

A Wikipedia editor is on a one-man mission to eradicate a grammatical error that really gets on his nerves.

Software engineer Bryan Henderson has dedicated years to removing the phrase 'comprised of' from the online encyclopedia.

The 51-year-old, who is known as Giraffedata online, has made more than 47,000 edits of the phrase to date.

Journalists Christopher Howse and Harry Mount discuss grammar vigilantism and their own grammatical bugbears.