No, JAG certification is not mandatory and cannot be a requirement for any consultant post. If you are ever challenged on this, please email askjets@rcplondon.ac.uk and we can send you a letter from our QA Training Working Group (QATWG) chair stating this position.
We recommend all independent endoscopists keep a record of their KPIs and some DOPS to use as proof of competence; if your trust has signed you off as a trainer then this will usually be sufficient.