It currently covers several areas of London , reaching Stratford to the north , south to Lewisham , west to Tower Gateway and Bank in the City of London financial district , and east to Beckton , London City Airport and Woolwich Arsenal . It covers several areas of London , reaching north to Stratford , south to Lewisham , west to Tower Gateway and Bank in the City of London financial district , and east to Beckton , London City Airport and Woolwich Arsenal .