>...they wanted hard stones as foundation rubble and these were stones in the vicinity ?<
Doubt it VBB. Take a look at the stone at the corner of Pewsey Church - http://www.liminae.co.uk/pages/england_wiltshire_pewsey_church.htm - it's a real beauty (smooth reddish surface) and a recumbent SS if ever I saw one. If it was just used as foundation rubble why leave it undressed and protruding in such a way when it would have been quite easy to cut and neatly incorporate it into the church foundations proper.
A second stone under the third buttress from the corner is also visible.