Is this a local stone or was it brought in from elsewhere during construction of the reservoir? Living locally I've made many trips to the surrounding moors and so far not seen evidence of any other rock art in the Rivington area.
From the Anderton parish council newsletter, Spring 2002ce
The Cup & Ring Stone
You may remember mention in a previous Newsletter of the Cup & Ring stone found in September 1999 at the edge of Lower Rivington Reservoir. The stone was found at a time of unusually low water level at the eastern edge of the reservoir (which was constructed in about 1850) at 10 metres below the high-water mark, so that as a rule it was visible only very infrequently. It was of a rather irregular shape, but its dimensions were roughly 80 cms in length. 55 cms wide and 50 cms deep and it was put on display at The Anderton Centre. pending examination by Lancashire County Council to confirm the 'genuineness' of the carving. To date we are still awaiting examination by a suitable expert .... more news on this topic in a future Newsletter.