Donald Macintyre's Sketch: Cross-eyed, myopic or just old-fashioned, soon these swivelling Tories will be making T-shirts

It didn’t take long to get to it. The Tory backbencher Edward Leigh, a strong opponent of gay marriage, was warming to his theme that the “outlandish views of the loony left in of the 1980s… have now become embedded in high places.”

Those “who disagree with these views are treated with hatred and contempt in order to marginalise their point of view.” By contrast, he himself, his wife told him, occasionally got “a bit cross-eyed” as he got older – but “if you call me swivel-eyed I could take you to court [for breaching disability rights].”

At this point the Labour MP George Howarth intervened: “ I don’t think he’s swivel-eyed, just myopic.” But pregnant, if oblique, reference to the now infamous slur allegedly made against party activists – and Mr Leigh was emphatic that his own constituency association strongly agreed with him – was not lost on MPs. Can the “Call me swivel-eyed” T-shirts and lapel badges be far behind?

Mr Leigh, a Catholic, was making a serious point about what he called the “chilling effect” of a regime of political correctness which had seen a housing association employee, Adrian Smith, demoted for merely saying on Facebook that “same sex marriage was an equality too far.”

But Margot James, the openly gay Tory MP who intervened later, was making a serious point, too. She hadn’t heard of this new “chilling effect” but she did remember the Eighties and Nineties’ “freezing effect on the lives of gay people and other minorities because at that time the majority were at liberty to discriminate against us in employment and every other walk of life, practically.” Not to mention the “outrageous verbal aggression that I recall from those days”.

Given that the Bill was David Cameron’s baby and that his party was deeply split over it, this was primarily a Tory day, of course, but the Labour MPs who would be guaranteeing the Prime Minister his majority took part in the debate, too. David Lammy argued if the Bill became law, teachers should not be allowed to promote opposition to gay marriage any more than the signs saying “No blacks, no Irish, no dogs” that his father had encountered as a Windrush immigrant.

And Labour’s Steve Doughty concluded his defence of the Bill with an eloquent appeal to MPs to remember the elated scenes in New Zealand – “the celebrations and the happiness that was in the House of Representatives there when they signed their own same-sex marriage legislation: the singing of love songs”. Looking across at some of the stony Tory faces on the benches opposite, he rowed back a fraction.

“Well perhaps not the singing”, he said.