Python Panel Slider Controlling Object material and World Sky Nodes at the same time?

Is there a way for a panel slider to control both an object's material node and a world node at the same time?

I currently have the slider controlling the mix factor of a material that is assigned to a background plane and would like it to also control the mix factor of the world environment textures.

    obj = bpy.data.objects["Sky_Sunset"]

mat = obj.active_material
if not mat:
layout.label("Create a material")
return

nodes = mat.node_tree.nodes

# Define the specific node
sky_colour = nodes["SkyMix"]

layout.prop(sky_colour.inputs["Fac"], "default_value", text="Sky Colour")


Any help would be really appreciated.

EDIT: As I had no responses I went a different direction in that I selected the Mix Node for the World and added a driver to the slider, I then selected the target to be the slider on in my panel.

I'm still interested to know the Python route.

EDIT 2: While the Driver route seems to work, on re-opening of the file the connection breaks.

• – batFINGER Apr 5 '19 at 16:42