Two boys aged 14 and 15 are still being questioned by police investigating the murder of an 85-year-old woman in Greenford.
Paula Castle was mugged in an alleyway beside a primary school on Monday afternoon.
She died in hospital the following day.
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Leaders of the Aslef union are recommending that their members accept the deal.
All inspirational people who have shown courage and kindness in the most difficult of circumstances.
Omid Saidy, 20, was attacked outside Parsons Green Tube station in west London on Monday evening.