Here is the conversation transcript between Joe, John and Varun (that is me). The context of the below conversation is as follows:
Context: Non-functional team (NFT) and Accessibility Centre of Excellence (ACoE) team need to collaborate as ACoE team want to setup the Centre of Excellence within an organisation. NFT team is responsible for providing various testers to the project team including accessibility testers.

Conversation Transcript:
John: Hi Joe, You was going back up the management chain to get a view on the overarching NFT team covering the gap between the level of assurance provided from a project handed to the CoE.

Joe: We spoke with Struan about the A11y Testers on the most part being a pool based out of NFT. I think we have agreement in principle. We did agree that most agile squads would need an A11y Tester permanently embedded in a squad - this would be required to truly shift left on RLGs A11y compliance as a whole. I believe it will become clearer with time just how many A11y Testers will be required. I suspect you guys are probably a bit optimistic on the number and the ACoE is pessimistic on the number (i.e. need too many) - let's not worry about the specifics of that at the moment.
Varun and I are still actively building out the Roadmap for ACoE and have made good headway. We will come back to you once we've got that and can share plans - Next week is my guess.

John: Embedding a specific Accessibility tester into each squad might not be the right approach. We are just ready to roll out a guide to what the performance team service can offer which can be used for Accessibility. Manage - Build, run and maintain the performance test suite, Support - Help build the test suite, provide guidance to the team/project on how to take things forward, Consult - the team/project are skilled up to build, run and maintain their performance suite. If a squad brings in a skilled accessibility tester to build, run and maintain their test suite. Once complete, they will have an expensive resource, at best, doing a side role when there is not accessibility testing to do. What the NFT team is offering is to engage with the team, provide hands on when needed, support through the process of becoming compliant and providing training/upskilling to whoever wants to learn on an ongoing basis.

Joe: I've asked Varun Padiyar if he is able to work this through. Varun, I think it would be helpful if we could have visibility of the guide John is talking about. Can you please send this to us John White? One note before I let Varun continue ... I dare say that you may be over simplifying by saying "Build, run and maintain" the suite. Yes, automation sort of runs itself once it is set up, and people are paying attention to the results. About 50% of Accessibility testing is manual testing and will be ongoing throughout the life of a product. We need to set ourselves up so that each agile squad has the ability to carry out necessary manual A11y testing for each of their work items in their sprints. Otherwise they will try to release a product that has not been fully A11y tested.

John:
Hi Joe, when I say maintain, I'm talking about the whole process. For each manual test, there should be a script that is followed so the test is repeatable, there should be knowledge transfer and upskilling, and anything that is automated there should a maintenance wrapper around it. The whole test piece in this area should have the relevant attention paid to it as you would expect with anything as critical, carrying such a potential impact on credibility, as Accessibility. I think we might be getting our wires crossed here. Also, we need to make sure that change which falls into a waterfall'ish type of bucket is also covered.

Varun: Hi John, thanks for sharing your thoughts. It’s great to have your expertise as we figure out how to best integrate non-functional testing services within our teams and ACoE.
I wanted to touch on why we might really benefit from having someone focus just on accessibility within each team:

Accessibility is specialised and having someone dedicated means we’re always on the ball with the latest guidelines.
With a dedicated tester, we can make sure accessibility gets the continuous attention it needs, which is crucial.
When we’re working quickly in Agile, having an expert around means we can sort any issues out straight away.
If someone’s trying to handle both accessibility and performance testing, they might not be able to give each area enough attention. Accessibility needs a full-time eye.
A tester who knows accessibility inside out will always keep our users’ needs at the forefront, making sure our products are inclusive.
Now, regarding the Waterfall projects, I fully recognise that their structure is more linear than Agile. However, the benefits of having a dedicated accessibility tester are just as important, if not more so. Waterfall projects can sometimes silo different phases such as design, development, and testing. A dedicated accessibility tester ensures that at each stage, accessibility requirements are clearly defined and met before moving to the next phase. This minimises the risk of discovering major accessibility issues late in the project when they are more costly and time-consuming to fix.
Having someone consistently championing accessibility throughout the Waterfall process embeds it into the project from the very beginning. This helps prevent any last-minute surprises that could delay project timelines and ensures a high-quality product for all users.
Let’s keep working together to create a process that supports both Agile and Waterfall methods, helping RLG lead the way in inclusive design.
John: Cheers for the above Varun, much appreciated. We might be tackling this in the wrong way. We shouldn't be thinking of working in a waterfall or agile way, Accessibility needs to be embedded in the work to be done from the start and, as we agreed, that needs the right lens applying. Embedding 'Accessibility' from the earliest point is key.

Varun: Yes John, completely agree with your thought. We always recommend that accessibility should be included right from the "ideation" phase.

John: The framework looks to put the onerous on project to get to a point in time where they have completed their assurance work, then sending this to the CoE to validate. This has a potential to create a bottle neck.Aside from that, embedding an Accessibility SME tester to each team/squad/project would not only be very costly but inefficient. A change could have no impact on Accessibility. The expensive SME would either be sat doing nothing or providing support for work that is below their pay grade. I'm not saying that an SME shouldn't be budgeted for, I'm saying it needs to be thought about and cost effective, which is something I've done on the performance area of NFT.

John: On Tuesday. myself and Varun had a conversation around if there was a need for the NFT team to provide any support in the process that change goes through on it's path to live and ticking all the boxes for Accessibility. Points captured from the meeting on Tuesday: -

Agreed that there is a skills gap at the moment with the understanding of Accessibility that teams and projects have, and what needs to be done to be compliant
This has the potential to impact project go live
Change being delivered in both agile and waterfall methodologies need to be compliant, they both need to be thought about and engage in the process with the ACoE
The hand over process and impact needs to be worked through
When will a project have to complete their Accessibility artefacts and provide them to the ACoE?
If this point is a large amount of time before go live this will impact agile projects
If this is small amount of time before go live, if major issues are encountered that require a lot of effort and time to fix, this will impact go live
Having a number of Accessibility SMEs in a small team, responsible for NFT, would significantly mitigated the above risks
To make this work, who ever is delivering this change should make appropriate adjustments to their budget at the relevant phase
The next step is to work out the engagement process that all parties should follow. This will identify any touch points where there might be friction. Varun, please add to this if you think I have missed anything.
Varun: Thanks John. These basically sums up our conversation. I would also like to add some additional points which can be useful:

Regarding the responsibility for ensuring accessibility implementation, it is important to clarify that while the ACoE governs accessibility in the organization, the ultimate responsibility lies with the project team. The ACoE is there to provide guidance, support, and ensure compliance, but it is the project team’s responsibility to implement accessibility correctly.
If at any point it becomes evident that the project go-live is being impacted by the ACoE process , the project team has the option to raise a deferment request. This request would allow them to proceed with the go-live while ensuring that any accessibility issues are addressed promptly in a future release.
Your task is to analyze the above conversation thoroughly and provide an engagement process that both ACoE and NFT team can follow.