Speaking at the opening of a library at South Ruislip in north west London, Mr Johnson said people could not swear at police and expect to get away with it.
If I read the papers correctly there was a proposal to arrest Mr Mitchell for what he said. That seems to be wholly common-sensical.
The public order act does allow for police officers' discretion in this matter. They've obviously decided not to go ahead with it.
But it shows the gravity of this offence.
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Maximum temperature on Thursday of 4C.
Tahira Ahmed, a mother-of-two, also suffered two broken arms in the 'brutal and ferocious attack' at the family home in May last year.
The closures are part of wider measures designed to revive the group's fortunes in the wake of a disastrous 2014.