I don't believe that where things currently stand with Advent, or CRL for that matter, is that great a concern. I do believe that both companies may play a major role when it comes to commercial production unless NWBO makes the determination to go it alone once they have the EDEN unit approved. I don't believe they'll go it alone, in fact I think just the opposite will be the case and both Advent and CRL may pay NWBO for leasing the EDEN units and the money they're paying will largely pay for them to be built. Clearly they'll make their money back, plus a lot more, by making, storing and distributing the vaccine as it's needed by patients all over the world in time.
I certainly don't know, but I suspect that these companies have agreements ready to be signed once the necessary paperwork is either filed with the regulators, or approve by them. As I see it, NWBO must make sufficient commercial production facilities to be available for inspection by the regulators before approval by any regulator. The UK is already approved, as you can't file the MAA until that's been done. The others, I believe, inspect and approve the facility as a part of the overall product approval package.
It's very possible that with EDEN the company chooses to do some of the commercial production themselves, and have some of it done by contract manufacturers, probably both Advent and CRL. It will be up to the company which way to go, but initially I believe they'll need existing capability at both Sawston and the CRL facility in Memphis.
Gary