(thanks Jeremy and Keith for feedback, even critical, and I was indeed prob. rushing too fast and too swollen-headedly with my post re. Ankerdine WOR - though I do think this PN contains Celtic contain *Anko "hook".  Depends on perspective, all this .   Sorry if I offended anyone.)

Hallo everyone,

ENBORNE BRK:
This one I saw a year ago, so much more considered - but I only bought OS Sheet 158 (Hungerford & Newbury) yesterday, and could then see that there must have been an "elephant" marsh feature at Enbourne, probably now drained (nearby PN Marsh Benham, Benham Marsh Farm etc.), so I'm feeling pretty sure about this now.

In France, Gaulish ana "marsh", (attested in the Endlicher Glossary), looks as if it may have been re-interpreted in PNs as
ducks (Latin anas, anatis, OFr an, anet) and, later, as donkeys (Lat asinus, ModFR ane).
See X. Delamarre's "DLG" for ana (cognate we learn with Eng. "fen") - and duck and donkey sections of Stephane Gendron's "Animaux et NL" (both Errance).
The record of forms for Enborne suggests that similar re-int. as "duck" stream occurred in the central Middle Ages.
(I suppose OE ened and Dutch eende etc must be cognates of Lat anas).
From VW:
ENBORNE "duck stream"
Aneborne -burna 1086-1223
Eneburna 1170
Ened(e)burn(e), -borne 1220-1353
     
This was orig. a RN of course (not the present Enborne River as EE and VW and MG in PN BRK make clear).

ANDOVER HMP
I'm less sure about this, but would like to suggest that this looks to me more like British "marshy steam(s)" than Pr W "ash-tree waters or streams at Onn" (VW).   
If so, it would be a PN of similar structure to Micheldever HMP and y Migneint N. Wales.
I should say as well that I don't think there are any instances of Welsh rivers with the structure proposed traditionally for 
Andover, i.e NAME OF SPECIES + -DEVER (-dwfr, -dwr etc. "water(s), rivers).
See RJ Thomas "EANC" (UWP) p. 50-51 where TREE rivers are listed (under Castan/Chestnut).

Andeferas c. 951 (15th)
(aet, to) Andeferan 962 (12th)

I don't know if there were marshes at Andover - but quite possibly, if I can triangulate backwards from the Anton Ponds
water features on the map.

MICHELDEVER HMP and y MIGNEINT (North Wales)
I have not seen these names compared before - but they always should be.
Owen and Morgan (PN Wales - Gwasg Gomer) say "swampy streams" I think for y Migneint
Mychnant 1592
Mikneint 1695
"uplands W. of Ffestioniog characterised by pools, bogs and streams"

I had always found it hard to credit EE's British etym. for Micheldever - but not since I noticed how very similar
the compound y Migneint is to Mycendefr 862 (12th) - VW "probably marshy waters".
And I do feel that  Andover wants to join this group.
What do you think everyone?
I'd see the Hants names as Br. not W. of course  

By the way, there is I think a real little cluster of old names between Speen , Enbourne, Inkpen - with another few that look as if they could use a rethink.   

Cheers for now and wishing everyone a nice week
Nick