Funnily enough British intelligence have got form when it comes to accusing politicians of being Russian assets. In the 1970s a group of right wing officers in MI5 were convinced that the Labour prime minister Harold Wilson was working for the KGB - they seriously believed the Russians had poisoned the previous Labour leader Hugh Gaitskell to pave the way for Wilson to replace him and eventually become british prime minister. We now know of course these ludicrous claims were the creation of a group of deranged right wing fantasists in the upper echelons of british society and part of a sustained campaign to sabotage and undermine Wilson's labour governments (with part of this campaign also apparently involving plans to stage a military coup https://www.theguardian.com/commentisfree/2006/mar/15/comment.labour1).
Course the US republican Trump's politics are a million miles away from those of a british socialist like Harold Wilson. But the motives of the british and american intelligence services in wanting to seriously damage Trump would seem to be clear and i suspect they are anything but altruistic motives. He doesn't back the so called 'rebels' in Syria (some of whom are linked to murderous jihadists like al qaeda and daesh it should be noted) and he has publicly endorsed Russian intervention in that country's civil war. For the hawks in US and British intelligence - and their Saudi allies - used to shaping the middle east along their own lines Trump's stance is tantamount to treason, and they have clearly decided the new man in the white house has to be made to toe the line when it comes to policy in the middle east and towards Putin's Russia.
That means toeing a line which has led to the near disintegration of at least 3 countries in the region - Libya, Iraq and Syria - and which has seen swathes of all 3 countries fall into the terrible clutches of the medieval homicides of daesh. And if Trump doesn't do what every president since Lyndon Johnson has done ie do whatever the US intelligence service tell him to do on the middle east and on Russia then i wouldn't rule out efforts to bring Trump's presidency to a premature end, either by constitutional means such as we saw in the summer of 1974 or by....er.... unconstitutional means as we saw on November 22nd 1963.