I believe they are employed by EVML so would be effectively jointly funded by GLL and Triathlon (and is there another social housing provider, not sure) which are funded by our rent. One way or another ultimately we pay for them since money does not appear from nowhere.
They have been helpful in telling my neighbours to turn their music off at unreasonable hours of the night. They can report contract-breaching behaviour to GLL/Triathlon (I know that I got someone an official warning from GLL for repeated music after midnight) and they can call the police, NEST, etc. as needed. Obviously they are not police officers so their powers directly are limited in terms of making people do things, but they have nice uniforms which is usually enough to get people to listen to them.