"The first stop is to consult the EPNS local volume...." someone
True enough if one can get at it and if there is a recent edition. For
example the Surrey edition dates from the 1930s and has some
identifications that would not be followed nowadays.
The first stop for the average user should be Ekwall's Oxford
Dictionary of English Placenames. I notice that one of those
replying on Eaton Constantine quotes his paragraph (without
acknowledgement, I'm sure that was just an oversight).
For Saltburn he gives the earliest form as dating to 1185 and the
meaning as "salty stream". For Constantine in Cornwall the earliest
mention is domesday book, "the church of St Constantine".
Of course in some places it may be impossible even to get hold of
this book....I know the feeling, stuck here in the middle of Norfolk
the nearest Encyclopaedia Britannica is 20 miles away and not
accessible without car parking difficulties
So if some kind person has one to hand and could look up
AMYAND for me and see if it was the name of a battle....
(and before someone says use the Internet, that told me it was a
town in Texas, which is not really relevant)