While many are sympathizing with Theresa May today, as she tries to push through a Brexit deal no one can agree on, they should perhaps spare a thought for currency traders.
A smorgasbord of political options lay ahead depending on the margin of defeat this evening, with real implications for British financial services, exporters and the economy.
The British pound has been in a holding pattern since the prime minister cancelled the vote last month, clinging to a $1.27 - $1.28 handle.
In the event of a small defeat: Broadly considered to be under 100 votes by currency analysts, they suggest the pound could remain relatively flat.
And what if the defeat is more substantial? A defeat over 200 votes could see it fall much further, but not by the dizzying drops we’ve seen in the last two and a half years of Brexit turbulence.
The pound dropped dramatically against the dollar straight after the referendum.
It dipped below the $1.20 mark at the start of 2017, in anticipation of May’s Lancaster House speech, where she would announce Britain’s departure from the Single Market.
It soared to $1.40 at the beginning of 2018, on positive noises that the EU would agree a close trading relationship with the UK.
Short of crashing out of the EU at the end of March, or a shock victory for the Prime Minister today, we’re unlikely to see such stomach-churning moves in the next few days.
You can no longer bet on a hard Brexit versus soft Brexit – there are more options than that.