As mentioned by DB, this seems to becoming a usual trait, and suggestions have been made that Humphs seems to be getting rid of managers at or around one years service, using a variety of the same 'excuses'.
I would suggest that turnover is not completely in the control of a manager (especially with one hand tied behind ones back), and in fact many other influences contribute, including external circumstances, brewery policies, and lack of training. Therefore I would suggest that the dismissal is 'unfair' and that it be challenged to seek compensation (rather than re-instatement - risk of further bullying). The brewery provides a fund for managers to take legal action, and also free advice and support is available from ACAS.
It's about time this kind of unjust, unfair, and inhumane behaviour - was stopped. If not, sooner or later Humphs is going to risk upsetting the wrong kind of person, resulting in personal injury at the very least.
It really does amaze me that in this day and age, someone can get away with causing so much harm to others, let alone allegedly breaking numerous laws!
One final note; It's by no surprise that Humphs hates any form of publicity, and goes the extra mile in trying to silence the truth, and gag his victims. I would probably offer him the opportunity to make an out-of-court compensation settlement for your silence, or approach the media, and see what the public's verdict is regarding the antics of H Smith.