A recent Commons vote on the EU Withdrawal Bill didn't apply a longstanding procedure allowing by-proxy and nodding-through votes by unwell MPs. Instead, they were forced to attend debates. Why did Theresa May's government consider this necessary?
At the time of writing, both sides (i.e. the Conservative and Labour parties) are blaming each other.
From a BBC News article:
Labour has accused the Tories of suspending a convention sparing unwell MPs from having to enter the chamber.
But the government blamed Labour for her ordeal.
Commons leader Andrea Leadsom said she was "particularly sorry" that Ms Shah, the MP for Bradford West, had been "forced to come and vote".
"But the fact that she had to come all the way from Bradford when she was clearly so unwell is clearly a matter for the honourable lady's party."
Labour's shadow Commons leader Valerie Vaz said she had heard Tory whips confirming it would not apply in Wednesday's vote.
"All the trust and conventions appear to have broken down that enable us to carry out our work here," she said.
In other words, it is not currently clear which side is to blame.
The Conservatives have a fairly small minority; the EU Withdrawal Bill is a high profile and contentious one, with a high risk of Conservatives voting against public lines. In this kind of situation, parties are likely to forego the usual "gentleman's agreements" and play hardball.
The minority Labour government of the 1970's is the standard example of such as stressful time when every vote counted, prompting John Prescott to remark on the lack of nodding through:
'In all my years in Parliament - even in the 1970s - I have NEVER seen this. This is absolutely bloody shameful.'
There is no procedure to allow votes by proxy: the house of Commons voted in principle for it but the implementation details are under review.
The thing that the Conservatives did that was unusual was to insist that ill MPs actually voted in person, rather than being 'nodded through', that is taken as having voted in person, although actually parked up in an ambulance somewhere in Parliament. The consensus appears to be that was taking non-cooperation a bit far, although one might take the view that "all's fair in love and war".
As to those Opposition MP's like Ms Shah turning up in an ambulance to vote, it's somewhat similar to filibustering or staying on a sports field when injured. Those involved endure physical hardship because they think winning is worth enduring discomfort. They don't get to transfer the blame to the other side.
TLDR: The Conservatives played unusually rough but both sides were determined to win at all costs.