It's down to the corrupt establishment elite
Forums are full of tripe like that since Brexit, unfortunately. Some sort of new-found arrogance with people who just want to troll everything and everyone. About half the people think that the BBC is right-wing biased. The other half think it's left-wing biased. Half think it's pro-Brexit. Half think it's anti-Brexit.
It's actually quite impartial, the polarised opinions are coming from the people in a country that has rapidly polarised itself in the last 12 months. People judge the BBC relative to their own political positoin, if it doesn't agree with that then it must be extremist in the opposite direction and therefore very very bad.
I wish peole would just step back and think. The BBC is actually a worl-renowned organisation known for its intergiry. Try to put your own prejudices to one side for a moment and look at from outside, compare with other countries. All this poltiical bravado, grass roots "rebelions", smugness and aggressiveness is what has got us into the this mess in the first place.
And getting back to the comment above - the "corrupt sestablishment elite". Ahem. That's just compeltely meaningless. Half the people think the EU is the corrupt establishment elite and right-wing parties like Conservatives and UKIP will lallow us to take back control, the other half see the EU as protection against the corrupt elite which they perceive as right-wing regimes like Conservatives and UKIP.
We are indeed in an extremely divided country at the moment. Everythign's quite even;ly split. Don't talk to me about the "will of the people" etc. The peoples' decision is basically that they are undecided on everything, there is no clear consensus (regardless of what Leave voters might tell you, or Conservative votes claiming that that they won the election). If the BBC displays some anti-Brexit news, then that's just as valid as pro-Brexit news. Just because it doesn't agree with what *you* think, doesn't make it wrong.