The Consensus existed. Liberal Democrats, two-thirds of the Parliamentary Conservative Party, and the overwhelming majority of Labour MPs supported the bill at the Second Reading. 91 MPs from the Conservative Party did not, as well as handfuls of Labour, DUP and smaller party MPs.
The UK's uncodified Constitution enshrines legislative responsibility to Parliament to act as the representative body to pass laws on behalf of the people. The House of Commons has power over the other place by virtue of its democratic mandate handed to it by the people through elections. In 2010 the people voted for parties that wanted to reform the House of Lords into either a wholly or mostly elected chamber. In July 2012, Parliament declared, through the Second Reading on House of Lords Reform Bill, that in principle it was in favour of exactly this.
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MPs therefore have a duty as Parliamentarians, to ensure that the will of Parliament is enacted. When passing a bill there is only 1 factor that matters, that it has the majority support of the house. No MP should forget this, and every MP should remind themself that they serve at the will of the people they represent. If Parliament feels thata decision should not be its' alone, then it can call a referendum, and allow the final arbitrayor to decide, the people.