GO 20 was launched today in Islington, London's first 20mph borough.
Children heard from Paralympian Danny Crates on how great it is to be active, took part in a safe cycling demo with Islington Council, carried out speed checks on traffic with help from the Met and celebrated 20mph by displaying their own banners and placards.
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In a wide-ranging Peston on Sunday interview, he said Parliament security needs reviewing and the PM's counter-terror strategy is flawed.
The terror attack carried out by Khalid Masood at Westminster that left four people dead lasted less than two minutes say police.
Two knives were found at the scene in Islington, North London, and the suspects fled on foot before being arrested.