The new Ward Panel handbook, as published by the Metropolitan police, states on page 9, Neighbourhood Watch with https://www.ourwatch.org.uk as the hosting site for the service.

Ourwatch is our main members’ registration portal for administration and practical purposes. We strongly encourage you to register with Ourwatch, even if you cannot find a scheme in your area as you will be able to benefit from the registration and get the crime prevention material and other communications sent by the local and national systems. You can always join a watch later, create your own watch or join a virtual cover watch on a social media site.
We also strongly encourage all to register with the Borough Association for membership.