Manipulated into dismissing unfairly: who’s at fault?

Not the employers, it would seem, as the Court of Appeal reversed the EAT’s judgement on the recent case of Royal Mail Ltd v Jhuti.
Officially, Ms Jhuti was fired for performing poorly, however the dismissal came after she blew the whistle on one of her colleagues to her line manager, a manager who then, motivated by this protected disclosure, proceeded to manipulate the decision to dismiss without being a part of the dismissal process himself. The EAT originally ruled that the employer should take the blame for unfair dismissal, despite the fact that the investigating manager acted innocently under misinformation fed by the line manager.
However, the Court of Appeal debunked this on the grounds that the employment tribunal only needs to consider the thought process of the decision maker, and only this person counts as the employer.
They also provided some useful information to employers by stating that, had the line manager had some responsibility for the investigation, the case against the employer would have been stronger. They were less explicit on what would be the case had the manipulator been nearer the top of management pile.