The BBC's Editorial standards are Here and it is clear that the BBC is paying for external lobbyists to break those guidelines.
This section is being specifically and deliberately broken;
Campaigns and Initiatives
4.3.17 The BBC must remain independent and distanced from government initiatives, campaigners, charities and their agendas, no matter how apparently worthy the cause or how much their message appears to be accepted or uncontroversial.
Based on that alone, there would certainly be grounds for the Secretary of State for Digital, Culture, Media and Sport (that'll be Nadine Dorris MP) to appoint an independent inquiry to scruitinise how widespread the BBC is breaking its impartiality code by financing the encouragement to break that code amongst its staff.
I don't reckon this on its own is sufficient to see the BBC lose its position as a State-funded broadcaster (the 'BBC Charter') but it would certainly be enough to justify a widespread clear-out of managers who don't comply with the BBC's ethos and stated ethics.