The first of two 48-hour strikes on London Underground began tonight with many lines reporting disruption.
Workers on the Bakerloo Line appeared to jump the gun with LU's website reporting "minor delays due to strike action" at least 20 minutes before the official 9pm start.
Shortly after 9pm the Jublilee Line was at a standstill between Stanmore and Waterloo with severe delays from Waterloo to Stratford.
A spokesman for the RMT union described the strike as "rock solid".
Commuters are warned to expect a limited service on many lines throughout tomorrow and Thursday.
Earlier, London mayor Boris Johnson urged the two striking unions, the RMT and TSSA, to return to the negotiations table.
RMT boss Bob Crow demanded the withdrawl of a consultation document on ticket office closures as a pre-condition for suspending the strike.
Prime Minister David Cameron described the strike as shameful.