Quick thinking from engineers prevented cement from setting in the Victoria Line signal room which would have caused even further disruption to commuters.
Peter McNaught, operations director for the Bakerloo, Central and Victoria lines, said it was lucky workers knew sugar would stop the cement setting.
Normal service has resumed on the line after engineers worked throughout the night to repair the damage.
More top news
An exclusive poll of the capital's residents for ITV London has found Labour would make sweeping gains if an election were held tomorrow.
Research into property prices has found London has more areas with an average price of more than £1m than anywhere else in the UK.
A permanent memorial will be unveiled today in memory of murdered Middleton soldier Lee Rigby.