Conservative MPs packed into the House of Commons to support the Private Member's Bill tabled by Tory backbencher James Wharton, which would require an in/out poll by the end of 2017.
Highly unusually for backbench legislation, the Prime Minister and other senior ministers including Chancellor George Osborne and Foreign Secretary William Hague were positioned prominently on the front bench to hear Mr Wharton introduce his Bill.
In chamber to speak on referendum debate Tory benches packed en masse they behave like pantomime characters
House of Commons is buzzing. Full Tory benches, lots of Labour - one Lib Dem. Good luck explaining that to constituents!
By contrast, the Labour and Liberal Democrat benches were sparsely occupied, with the bulk of the parties' MPs obeying the guidance of their leaders to stay away from a debate which they regard as a political stunt.
More top news
Spring takes a hike - for the time being
A number of Britons are feared stranded on Mount Everest after the Nepal earthquake triggered a deadly avalanche on Saturday.
Prime Minister defends royals' decision to give birth in a private hospital - instead of going with the NHS