Boris Johnson was booed and heckled by an audience made up of hundreds of campaigners last night.
The Mayor was confronted about the downgrading of services at Lewisham Hospital at People's Question Time in Catford.
Ronke Phillips reports:
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Official readings are recorded three metres in the air but a study found levels of nitrogen dioxide (NO2) were higher at pushchair level.
Tubes, trains, trams, buses, cable cars, river buses, taxis and going by foot - your guide to getting around during the strike.
Union officials rejected a revised offer from Underground managers during a meeting at the conciliation service ACAS this afternoon.