Sycamore sick?

A thin trunk of ivy-covered sycamore was threatening our telephone line so six months ago I cut it off. The rest of the tree appears fine but a vivid orange gunk is now flowing out from the stump and dribbling down the side. This has been going on for about two weeks and probably coincides with rising sap.

Sycamore gunk

Does anyone have any idea as to what it might be?