I assumed the domain was derived from the `TRUST_DOMAIN` ClassAd which is set to `gridpp.rl.ac.uk`. Is this new format of `condor@password` expected?
This may be related to HTCONDOR-2486, where we changed the default user ID for the PASSWORD method from `condor_pool` to `condor`, but I'm not sure why your old config worked, so I'm clearly missing something. (You don't appear to allow `condor_password` to write master ads to the collector.)
-- ToddM