I have three shipping modules.
 
I want to be able to restrict one category of products to be shipped by ony two of these shipping modules. (or prevent them being shipped by one of the modules)
 
Shipping rules allow selection by country but not by shipping module.
 
Does anyone have any suggestions to work on, please?

I'm sorry Chris, I've looked all over through their options and settings, and cannot find this option. It's surprising though, as you would think this would be a common situation.
 
Sorry I cannot provide a better option to you, as the only way I found a way to do this, was to force certain weight requirements on it, and then do custom pricing that was fixed for shipping.

Thanks Dan - I use the weight route you suggest to manage shipping though the UK postal service - but this then makes it impossible to use weights for other shipping methods (where I use price) - as the 'forced' weights negate the option.
 
Chris