Super, thanks Dr. Sassi I will try that.
One of the issues I found with my method of keyframing the Display tag > Visibility is that when the opacity is 0% it stills casts a dark shadow but if I start it's opacity at 3% there is no shadow initially and as the opacity increases to 100% the shadow and object fades in as normal, so that might be a work-around.
But I will also try your method and see how it works. Thanks for taking the time to answer my query

Hi there. I have been given a 3D model that uses 20+ textures and I would like to be able to fade the model on and off. I've tried using the visibility setting on the display tag and it leaves a black shadow whilst fading out which isn't working for what I need.

I know that I can animate the opacity directly in each material but rather than animate all 20+ materials is there a way for one node or controller to control the opacity of all the materials at the same time?

So I only have to animate one value and it changes the opacity of all the materials

Thanks in advance.