Trevor
Just to add to the positive advice so far: If you don't know much about the manager involved, it might be worth finding out more about him during informal chats with others, including the boss. Obviously try to be tactful and diplomatic when doing so, especially if you aren't sure what the others think of the manager (or you as the relative newcomer!) or how well they know each other, whether at work or outside it (e.g. fellow golfers, etc.)
The information you glean might for example simply confirm that the guy is awkward with most people. Another possibility is that problems in the past with OS&H adversely influence his attitude to you in your role (or what he might perceive it to be - e.g. another interfering jobsworth always banning things) rather than you as an individual.
After that, according to your information and judgement, you might consider trying to have a tactful chat with him when an opportunity arises. The element of surprise might work in your favour. If possible, try to find out what bugs him about OS&H, tell him how you see your role (supporting, enabling, etc. but not banning). During my time as an HSE inspector, I sometimes found this approach worked - especially if I knew from HSE documentation that a previous visit had been paid by an inspector known to be officious.
If you still don't get anywhere with the manager, then have a word with your boss and mention that you've tried directly with the manager but to no avail. Again tact is essential. The boss and the manager may know each other well and/or the manager has been with the organisation a long time. If he is regarded as good at his job, others in the organisation, including your boss, won't want necessarily the status quo disturbed, especially by newcomers.
Also, to echo Ron H's advice, all forum users should remember that this is a public forum, so be careful what you write on it, especially if using your own name and not a pseudonym. Also, despite using pseudonyms, some users are fairly identifiable from the information which appears beneath the pseudonyms and/or what they write on the forum!
Occasionally I've done internet searches for topics or names which appear on this discussion forum. However, though search results in the past did include postings on the previous version of the forum, those on the current version do not appear. As this applies even when I do searches using my home computer, I can't blame my employer's ICT system which, like many others, is set to block access to websites categorised under 'social, discussion' or similar. Thus, though relevant parts of the IOSH website DO appear during searches under terms like IOSH forum or IOSH discussion, it seems that casual searches do not reveal this forum.