Callander - PV's Grave, Rob Roy Way

I came across this small cairn with what appears to be a headstone at the side of the Rob Roy Way track. It's about 500m uphill from the car park at the East Lodge entrance to the Invertrossachs Estate at NN 59064 05247. It is not marked on the OS map, nor on Canmore or Pastmap as a HER. It appears to be a grave with the small headstone showing the initials P and V, which are separated by a large ornate T shape, somewhat like an inverted anchor. The style and crispness of the lettering looks, 1920s-ish, possibly earlier. I would speculate that this is the grave of two pets - the P and the V. A single pet I'd think would have its full name on the stone. The cairn is low and almost circular or a shallow oval with some quartzite rocks deliberately incorporated.