Two Brighton and Hove MPs voted against triggering Article 50 by the end of March, formally starting the process of leaving the European Union.
More than two thirds of voters in the city backed the country remaining in the EU in June’s referendum.
Last night MPs backed a Labour motion, arguing that the Government for publishing a plan on Brexit and it was Parliament’s responsibility to ‘properly scrutinise the Government’, by 448 votes to 75.
But a Government motion, which added that its timetable for triggering Article 50 of the Lisbon Treaty, which will see formal talks to leave the EU start, should be respected.
Both Green MP for Brighton Pavilion Caroline Lucas and Labour’s Hove MP Peter Kyle voted against the Government’s amendment.
In the House of Commons, Dr Lucas argued that Labour was ‘falling into a Tory trap’ by supporting the invoking of Article 50 by March, which she called an ‘unrealistic and arbitrary date’.
She said: “I cannot support the Government-amended motion, which threatens to throw Britain off the Brexit cliff edge, with a vague plan at best and within a timeframe that simply is not compatible with developing any sort of coherent strategy.”
She wrote afterwards on Twitter: “Sadly tonight Labour gave ministers a blank cheque for hard Brexit - no preliminary White Paper required & arbitrary, unrealistic timetable.”
Mr Kyle added: “Just voted against Government amendment calling for A-50 submission in March. Trigger when we’re prepared for negotiations, not before.”
Robin Walker, a minister at the Department for Exiting the European Union, said: “After the arguments and the division of the referendum, now is the time for people to come together and work together to ensure that the UK succeeds.
“By supporting the Government amendment, colleagues from across the house can show they have heard the will of the people and that we will work together to make a success of it.
“We can move forward with the process of making this work not just for 48 per cent or 52 per cent, but for 100 per cent of the people we represent.”