However, an internal document obtained by the Independent on Sunday reveals that Mr Gregory, the powerful West Midlands regional secretary of the GMB union, is under investigation following allegations by his staff of "bullying, harassment and intimidation".
The pounds 46,000-a-year regional secretary, one of 10 in the union, is accused of "belittling and humiliating" staff.
The document, which is now in the hands of John Edmonds, the union's general secretary, states: "Some officers who have tried to approach the regional secretary have met with responses that have meant they are afraid to pursue the matter further."
Within the past three months three officers, who were off sick with stress- related illnesses, have been dismissed.
The union is also facing a sex-discrimination case which has been lodged at the Employment Tribunal, and there has been a preliminary hearing into alleged disability discrimination.
There has been virtually a 100 per cent turnover among officers in the region since Mr Gregory took over four-and-a- half years ago, it is claimed.
Mike Robinson of the MSF white-collar union, which represents some of the GMB staff said: "If any one of the accusations is true - and I have no reason to doubt any of them - it is an extremely serious situation, especially as the GMB is a party to the TUC anti-bullying charter. The union should begin an independent investigation immediately, possibly suspending those who have been accused of bullying while the inquiry is carried out."
A spokesman for the GMB said: "Allegations and complaints have been lodged against Mr Gregory that will be processed within the union's normal procedures. Once they have been completed, the findings will be made public.
"A number of those who have made allegations have themselves just been the subject of a vote of no confidence by colleagues."Reuse content