Hi Charles,
I can't see Andrew and Eleanor's marriage in Hambleden 1837 or before.
As for Eleanor's baptism around 1815/16, these are the only possibles:
born Oct 28, baptised Nov 26 1816 Eleanor d/o John & Sarah AYRES, labourer.
born 13 Aug, baptised 21 Sep 1817 Eleanor d/o James & Martha CLEMENTS, labourer.
I checked 1810-20 and there is also:
born Apr 8, baptised May 2 1813 Eleanor d/o John & Mary SADLER, labourer.
Up to 1837, there are no burials or marriages in Hambleden for any of the above 3 Eleanors.
So, if she gave the correct info on the censuses, she should be one of the above- perhaps you could track the others to see if they married other people?
Jill