Understand - there are 650 members of the House of Commons.
This vote - non binding - got 274 votes or about 42% - and it only got that because Labor required its members to vote for it under party discipline and some of them would have done so only because they knew it wouldn’t actually have any effect.
The actual government of the United Kingdom, for the most part, didn’t even dignify the debate by attending - which is why the No vote was so low. Again, if the vote had meant something, about 300 MPs would have turned up to vote no, but with this type of debate, it’s generally considered better to treat it as irrelevant rather than dignify it with a response - you just put enough MPs into the House to require a counted vote, not just a voice vote.
The Westminster system is quite arcane and complex in its traditions, which makes this look like a bigger deal than it actually is to those who don’t know the system well.
Then why did the majority run away from it and even allow it?