Up until 2010, I viewed the BBC as a pretty politically balanced broadcaster, although one that had ties to and was very supportive/protective of the old-school Establishment. Not in a pernicious way,; more like a benevolent lord of the manor and well-meaning family.
Through the Thatcher, Major & Bliar years, I did not see a bias (so the argument made about every government making political appointments to senior BBC positions, which in turn lead to a bias within the corporation, is groundless)
The British (English?) right, like the MAGAwits in the US, hated the balance. Used to most of the media propagating hard-right positions as 'normal' (shunting the Overton window some distance rightwards), they viewed the BBC as lefty. The same right-wing print media, through their endemic gaslighting, reinforced the erroneous opinion that the BBC was left-biased.
The Tory Party themselves put into action their plan to bring the BBC more under their control after the 2010 GE. There were stories from whistle blowers of interference in news editorial direction and threats of 'privatisation'. Labour, under Miliband, were moved to formally complain to the BBC about their pro-Tory bias (
https://www.theguardian.com/politics/2011/dec/31/ed-miliband-labour-bbc-bias)
When the odious Whittingdale took over at Culture, Media & Sport, bully-boy interference and threats ramped up. The bias is subtle. A study into BBCs coverage of the 2015 election campaign showed how they focused on policy areas that were key Tory strong points with the public, whilst relegating focus on policy areas (like underfunding the NHS, education and public services) which are strong for Labour.
All this notwithstanding, I still support the principle of a national broadcaster funded through a licence fee (or similar). But when that entire neutral ethos is being corrupted by a political party abusing their position to strongarm the broadcaster into presenting a biased news agenda in favour of that party, it presents a dilemma: does one continue to stick rigidly to one's principles even though it brings a large electoral benefit to the Tories? Or do you shout that the BBC is being abused by the Tory Party and try to bring attention to this Orwellian corruption?