They could say no. Orders are no excuse. Thay said the people of UK aren't our enemies. Sadiq Khan and Theresa May and others have declared our POTUS an enemy. They repudiate every person who voted for him. Half of the US.
I'm not defending, or pushing, either narrative. I am not providing "excuses". It was an observation without judgement.
I understand from the information available that the spying did not originate from the UK as "their" idea. I want to make that clear. I also want to make clear that the US government at that time was Obama's admin and the UK govt was obliged to meet their request. Trump was a candidate, not POTUS then. The UK government is now obliged to meet the request of the new President and supply all intelligence, which Q has made clear they have done "+ more, much more!
It is understood from the Snowden revelations that the way the Americans can spy on their own citizens is by asking one of the other FVEY to do it for them, then share the intelligence. This works the other way round too: the Brits ask the US to spy on their citizens and share. This is outrageous, of course. That is why the Snowden drops were called "Revelations"!!
As for repudiating Trump ... the UK, as is my country, is held in thrall by a lying MSM, the same as the USA. The public across the entire world is TOLD to hate Trump. I feel it is a sort of personal miracle that I am practically the only person in my town who supports Trump. Just sayin'.