The role in outline
The business sponsor is the executive accountable for a programme achieving the outcome that justified its funding. The role owns the business case and its benefits, secures resources, arbitrates priority conflicts, champions the change among peers, and remains accountable after go-live, when the benefits are supposed to arrive and the programme team has dispersed.
Why sponsorship is the strongest predictor nobody staffs properly
Delivery teams can manage everything inside the programme boundary. Everything that kills programmes lives outside it: a peer function withholding its best people, a competing initiative claiming the same change capacity, an executive team whose attention has moved on. Only the sponsor operates in that territory, and doing so costs something real, favours called in, colleagues confronted, the sponsor's own credibility attached to a result they cannot fully control. That is why sponsorship cannot be delegated and why its quality is worth assessing before approval as deliberately as the plan itself: a first-rate plan under an absent sponsor loses to a mediocre plan under a committed one.