Occ Health says I'm fit to return to work, employer says I'm not

Brie

Seems to me this is the same as a fit note in that a note from your doctor might say you are well enough to return but your employer says no.  People think that the employer has the final say when in fact if you are deemed fit then it is your decision to return to work.  The only proviso I would add to this for your situation would be if your employer/immediate manager knew that your back problems are made worse by standing for long times and they know that you will be doing a lot of standing over the coming months due to training people or something similar.  

Which puts you in the position of trying to understand why your employer doesn't want you back at work.  This might be resolved with a simple meeting with you, manager and union rep and perhaps HR to discuss in a civilised way rather than either side getting confrontational about it.  

strawb_shortcake

I've recently put someone through OH within the civil service, it was made very clear that recommendations from OH were purely advisory and non binding. When my member of staff decided they wanted to come back to work I didn't say no but did suggest that the option was discussed with their Dr not just OH. 

If this is a repeated sickness leave of the same condition I'd be concerned that the job may aggravate it more. In the event the job did make your back problems worse then its your employer not OH that would be accountable