Basically what I understand from it is that NR are trying to create a countrywide system that is operated by the least amount of boxes, an example of this is that East Anglia will have only one signal box that controls every signal and track for the whole region, these will be operated by switches rather than levers and will create a cost saving by the need to employ signal men, hence the word modular, also note new crossings that are operated by sensor too
Modular signalling only refers to the modular nature of the local interlocking and local hardware, as mentioned earlier in
John55's reply to me in post #42. It will only be seen on relatively simple layouts, such as a straightforward two track rural railway. No-one has suggested that modular signalling is the solution to every resignalling project, they aren't likely to use it for the Waterloo area for instance.
The move to Regional Operations Centres, (ROCs) is a parallel process of consolidation of all the different operating panels in a region (or NR route) into massive buildings, basically one for each region. However that is a separate development, clearly some simple route resignalling using modular equipment will ultimately be re-controlled into a region's ROC, but you can do that without modular hardware. As I mentioned earlier, the Exeter - Salsibury resignalling is
not considered modular, but it does use lightweight signals. It wouldn't be resignalled again just to move control into Basingstoke ROC from Basingstoke New, (which will apparently only have a life expectancy in single figures as it happens).
In summary then it seems that modular signalling can happen any time, but it is not actually a
pre-requisite of recontrol into an ROC. All the existing panel type boxes will just get re-controlled remotely.