Coroner Sir Robert Owen has upheld a request by Foreign Secretary William Hague to keep secret any evidence that Russian state agencies may have been involved in Alexander Litvinenko's death.
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She met with the families of children who must stay near the hospital.
Six people, including three children, died in the fire at Lakanal House in Camberwell in 2009.
PCs Gavin Bateman and Tony Stephenson spent 30 minutes drinking tea.