Nine Stones Close cup marked stone

From Nine stones Close circle and with your back to Robin Hoods stride walk downhill to the right hand corner of the field and go through the gateway, turn left and follow the wall to the gateway half way along and go through it, turn right and walk around 10 metres down the wall and the cup stone is on top of it.

I’ve never heard mention of this stone anywhere before, if you know different could you post the info please.