Well, when John Aubrey drew the remains of the Devil's Quoits in Monumenta Britannica in the 17th century, there were only three stones still standing.

By the time that the military arrived, in the 1940s, to place their airfield over the henge, there was just one stone left in situ.

That stone, plus at least two other old stones from the vicinity, now stand within the circle. They are made from the conglomerate stone found locally.

So, I think your informant has told you a load of bollocks.