The Mayor of London Boris Johnson said: "London is home to almost half of all people living with HIV in the UK, but a quarter of them are unaware they carry the virus.
"It is vital that people who might be at risk get tested, not only to reduce the risk of transmission to others, but to ensure they get the life-saving treatments that are available."
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Fahima Begum was found hanged at her east London home, after a friend called 999 to say she had sent him a suicidal text.
Members of the RMT union on Southern Railway and parts of London Underground staged 24-hour walkouts.
The couple, in their late 50s, were asleep when the two masked men entered their room in Ilford, east London, in the early hours of Monday./