The news that Mr Knight was leaving his job broke last week (LGC, 16 February). LGC understands a personality clash with Ms McDonagh played a part.
A Westminster source said Mr Knight was frustrated because his ambitions to do more with the unit were being blocked.
Mr Knight told LGC there was no work going on to recruit a replacement and he would stay in the job for the foreseeable future.
In a letter to LGC he denies he resigned 'days before Labour's spring conference', saying he had indicated to the party last year that he was likely to leave. He described some of the reporting of his departure as fanciful.