Tens of thousands of commuters suffered travel misery tonight as services on busy rail lines were crippled by strike action - with further disruption due tomorrow.
National Express East Anglia ran just 100 services instead of the usual 1,800 because of the strike, with managers standing in for the strikers.
A limited number of trains ran on routes, including those between London and Stansted airport, Southend, Norwich and Colchester, with the company admitting that passengers were suffering "severe disruption".
The Rail Maritime and Transport union and Aslef said their members "solidly supported" the walkout, over pay and working conditions, which is due to be followed by three further 48-hour stoppages in the coming weeks.
The strike took place as National Express revealed it slumped into the red in the first six months of the year as it lost more than £20 million on its soon-to-be nationalised East Coast rail line.
The group reported interim pre-tax losses of £48.1 million against profits of £52.4 million a year earlier as it also set aside a hefty sum to cover its exit from the East Coast rail franchise, which is being taken back into Government hands later this year.
Bob Crow, leader of the RMT, said: "We expect exactly the same response from our members tomorrow, with a similar effect on services.
"This strike has been caused by greedy National Express bosses who have soaked up £2.5 billion in taxpayer subsidies in the past 10 years and who have milked every penny out of this franchise, while treating their staff like dirt."
Andrew Chivers, managing director of National Express East Anglia, said: "The unions' demands are totally unrealistic, especially in this current economic climate.
"We have offered salary increases above the rate of inflation, and remain available at any time for discussions to reach a sensible, affordable and fair agreement.
"Strike action is unnecessary, simply not the solution and I would like to apologise to our customers."
Aslef general secretary Keith Norman said: "National Express is responsible for the total mistrust that exists between the company and their train driver employees.
"The dispute is not just about pay, but also about the poor industrial relations that have existed in this company for a long time - with little genuine effort being made by the management team to resolve issues between us."