I switched to the HB_Bridge branch and it performed a little better, in that hb_confbridge was relaying the frames to the parrot, however the parrot was still ignoring them.
I did some digging and found this was due to the fact that hb_confbridge was relaying the frames with the Radio_ID of hblink, rather than that of the Parrots 'client', so they were dropped.
I've resolved it by re-writing the RADIO_ID of the frame is being relayed to a master. I will submit a PR in due course, however I think I must be missing something as I'm surprised this hasn't picked up in the past.
Is it unusual / unsupported for conf_bridge to bridge two Masters?