I just want to say that the BBC has had partisan claims by people from all the aisles. The BBC tends to be more left leaning and progressive with a lot of its coverage, I'm assuming that's mostly because journalists tend to be, however there have been certain "coincidences" when it comes to Conservative coverage.
I don't know whether or not they're partisan, but I feel when both left and right leaning people call the BBC partisan, it feels like they're less likely to be partisan.