Thanks ICLOK , one assumes therefore that it is the house for the 50 '' pumping engine that still stands, although it did not seem a very big house for a 50'' engine .
At a guess the stamps engine may have been immediately adjacent to the north / east side of the pumping house as there are the remains of fairly substantial walls immediately next to the pump house . If this is not the case then the stamps engine house has completely disappeared, possibly the granite blocks from the stamps house have been used to build up the bob wall of the engine house to convert it to a residential house , certainly the conversion has been very welll done many many years ago.