Jo Swinson should have voted in the Commons on Tuesday despite being on maternity leave, Kate Hoey has said.

Speaking to the Spectator podcast, Hoey said: “I gather she was OK to go on an anti-Trump demonstration so I’m not clear why she wasn’t able to come and vote.”

Swinson was ‘paired’ with Tory chairman Brandon Lewis for crunch votes on Brexit legislation this week, meaning neither would walk through the voting lobbies – cancelling each other out.

But Lewis reneged on the agreement and voted, prompting calls for the Conservative chief whip, Julian Smith, to quit. 

Laura Gordon, the Lib Dem candidate in Sheffield Hallam, hit out at Hoey. “Maternity leave doesn’t mean you’re confined to the house till you need to go to work,” she said.

“Plus the point isn’t whether Jo Swinson was physically able to vote but the fact that she was told she was paired and it turned out the government cheated.”

And allies of Swinson pointed out Hoey’s remarks betray a wider misunderstanding of the pressures on breastfeeding mothers.

Engagements that can be cancelled or curtailed  at short notice, like attending part of a protest, are very different from firm commitments for hours on end like commons votes, they added.

The decision for Lewis to vote has led to uproar on both the opposition and Tory benches, with MPs furious the pairing convention has been undermined.

It has led to renewed calls for a system of proxy voting to be introduced in parliament, so MPs on maternity leave can nominate someone else to vote on their behalf.

Commons Leader Andrea Leadsom has said there would now be a debate on proxy voting, which would end the need for pairing, in September.

Hoey said while she did not see why Swinson could not vote, “clearly the pairing system needs to be looked at it’s not working very well the trust has broken down”.

Theresa May insisted Smith and Lewis had made an “honest mistake” amid demands that they both resign.