So the upshot of this:

"A key element of BT's revised strategy has been to install products initially as "standalone" deployments and then to integrate them with the cluster-wide solution."

... is that they are installing standalond products that could have been deployed four years ago, then they will (claim to) worry about spine integration later?

So this will be like the cluster PACS rollout where NPfIT can claim success in deploying standalond products that - in most cases - would have been deployed by the individual trusts by now regardless, and then spend years trying to integrate them with little or no success, all at considerable extra cost thanks to the flotilla of LSP project managers sitting in on every meeting and discussion.