If you want to watch the reality of modern politics being played out in real time, you could do worse than visit the Parliament petitions website. The petition to prevent Donald Trump from making a State Visit to the UK has now got well over a million signatures. Rather like the spinning figures on a petrol pump, you can see the total rising by the hundreds every minute as people register their moral outrage at the President's executive order banning travel to the US from certain Muslim majority countries. What price should we, as a nation, be willing to pay to make it clear to a foreign nation that their policies are unacceptable? Publicly humiliating Donald Trump by withdrawing, or downgrading, his state visit would certainly send him a message and might win us the equivalent of a diplomatic round of applause around the world, but what impact would that have on our ability to negotiate a favourable trade deal with the US? Would that be a price worth paying? If you draw the line at Donald Trump, how do you feel about the UK signing a £100m arms deal with Turkey - a country that, according to some human rights groups, jails more journalists than any other? These are questions we'll increasingly have to answer in a post-Brexit world where we need to sign deals to replace the trade that might be lost on leaving the EU. People talk euphemistically of "holding their noses" and "supping with a long spoon" in the national interest, but how far should you morally compromise to keep the bottom line in the black? Producer: Phil Pegum.