An unqualified teacher who arrived at school smelling of alcohol and told a colleague to “fuck off” has been banned for life from the profession.

A professional conduct panel of the Teaching Regulation Agency found no mitigating circumstances for Joseph O’Brien, an unqualified English teacher and form tutor at Gretton School, Cambridge.

He was found to have arrived on at least three occasions smelling of alcohol at the independent special school for pupils with autism or Asperger’s syndrome.

Mr O’Brien was also found to have raised his voice and responded in an aggressive manner to a member of the school’s management during a staff briefing, in which he asked her: “What’s the fucking point of SLT if, when I send an email…” and later told her she “could ‘fuck off’, or words to a similar effect”.

The panel accepted “compelling” evidence from the staff member concerned and noted that Mr O’Brien had said in a statement that he “could not confirm the words I said…I was affronted…I reacted in a way that was indicative of the mood I was in”.

It also found that Mr O’Brien took two pupils for walks outside the school, which was “not acceptable practice at the school”, in one case declining the offer of a chaperone.

However, panel members rejected claims that he made an unauthorised visit to a pupil’s home and that he offered to take the pupil for a walk to impart “a secret”.

The panel found Mr O’Brien failed to moderate his use of alcohol or abuse of staff members “despite the concerns of colleagues being repeatedly explained to him”.

He also “cultivated troubling and unhealthy relationships with pupils that reduced their independence”.

The panel noted his lack of remorse or insight and concluded there would be a real risk of such behaviour being repeated, meaning “Mr O’Brien would, therefore, be a danger to pupils should he be able to teach again”.

It banned him from teaching for life with no review permitted, and Department for Education decision-maker Alan Meyrick agreed on this.