The BBC’s Editorial Guidelines explain that “evidence based judgements” are entirely compatible with impartiality: Professional judgements, evidence-based assessment

It is the role of the BBC’s senior on air editors to make judgement calls in their reporting, which is something they do every day. Having attended the news conference in question, covered the many pre-Budget twists and turns and been briefed on the day the Financial Times revealed income tax rates wouldn’t be raised, Chris concluded we had been misled in one particular way around tax receipts.

This came to light after the unprecedented decision of the Office for Budget Responsibility to set out publicly the timetable of when it had shared its work with the Treasury. Chris, in consultation with senior colleagues, then concluded he should share this judgement with audiences. They were aware this would be seen by some as significant. Chris scripted what he would say on the Today programme and in the BBC News Online article and this script was seen by senior editors before broadcast, to ensure precision in what was being said. After Chris had made his assessment through careful consideration and consultation, it was important to communicate it transparently to audiences. 

Chris was clear about the point he considered was misleading, but he has also been careful to include ‘right of replies’ and alternative views in his reporting.