Your own choice. Questions for you to answer: Is he any good? What is your policy on using external experts? Does the audience "get it"? Is there a standard or academic Level that needs to be achieved? Is he delivering his own material, yours or somebody else's.

Hi Rich - in answer to your questions:- 1 - neither your trainer nor the course itself legally require any form of certification. 2 - just because he was a firefighter who taught fire safety and fire warden stuff doesn't mean that he's actually competent to do either. 3 - is he sufficiently knowledgable with regard to current law and practical aplication of it? 4 - what do you require of your fire wardens anyway? There is no legal definition of the term nor what they might be required to do so you should ensure that any training is explicit to what yours actually do. Frank Hallett

Whether the person needs to be qualified to teach the courses you want depends on the course but I would urge you to get the person onto a teacher training course specifically for teaching adults. I have never met anyone whose classroom performance is not enhanced by going through some form of teacher training - those who believe that the teacher only needs to know the subject they are teaching not how to communicate that knowledge are condemning their staff to a poor learning experience.