If I remember correctly, Hunmanby Station ABCL, for movements on the single-line towards Bridlington, doesn't have a DCI. Instead it has a two-aspect c/l section signal that incorporates the function of the DCI. In other words, the signal will only clear after the route has been set, the conditions in the route have been met, the ABCL has been called and barriers proved down, etc., for 30 seconds. If there is a failure of the route, but not the level crossing, then an emergency plunger is available for use under the instruction of the signaller, who (I assume) can authorise its use and permission to pass the signal at danger.
So there's one instance of an emergency plunger associated with a signal, but I would guess they're as rare as hen's teeth, as my old supervisor used to say!