London's top police officer, Commissioner Bernard Hogan-Howe, gave a lesson on the dangers of knife crime to teenagers at Edmonton County School - including the friends of a pupil who was killed last year.
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The pub owner said the sign is a nod at having a bit of fun in support of them and celebrating their relationship and the wedding.
A 61-year-old woman was taken to hospital with head injuries after the incident in Islington, north London.
Assema Kedir Habib spoke at the commemoration of her brother Hashim Kedir and his family.