James Deacon in Berkshire conundrum

[Frank Toms]

Sorry, Jacob not Abraham, but still not a super common name, should be able to drill down into that one.

[Sloe Gin]

Someone mentioned a booklet produced by the East Ilsley Family History Society about the Deacon family in particular, does anyone have it or a link to where I can buy it online?

Not about the Deacon family, sorry.  The one I quoted from was an unofficial census drawn up by the curate about 1831.  He was about to hand over to a new incoming Rector, and wanted to give him a heads-up on the parishioners.  He was quite rude about some of them .... 

[Sloe Gin]

That marriage was at Rotherfield Greys, Henley On Thames, so 20 miles away from East Illsley - not outwith the realm of possibility but you've got me questioning it now though. Elizabeth and Deacon are really commons names back then, Abraham Jacob less so but I'll do some digging to make sure I've not got the wrong people.

Betty though.  Not nearly as common as Elizabeth in official records.
I wouldn't worry about the marriage being a few miles away.  People moved around for work, especially agricultural workers; and perhaps Betty's parents moved there.  Might be worth looking for them in parish registers after 1809.

And being new to this I'm a bit lost once the birth records run out in 1837 - what's the best way of tracing people back to the 1700s, can it be done online or is it more about looking up local historical records in person?

Can be a bit of both, and as online sources are continually being added to, it pays to keep checking. 
For Berkshire, the FHS has CDs compiling baptisms, marriages and burials - in various stages of completeness.  Transcriptions only though, but still useful. 
Wills are another source that can provide vital information and fill gaps.

[Frank Toms]

James & Sarah (Stanmore)  baptise a daughter Betty at Blewberry in 1809
https://www.familysearch.org/ark:/61903/1:1:JSJN-J8D

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Edit - never mind, re-reading the thread I think everything below is explained in previous posts.
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Oops, I missed this the first time round - so for my tree, I think this Betty (1809-1874), married James Deacon (1810-1874) in 1832, and had the following children (all appear on census docs but some don't appear on GRO for some reason, possibly under different first names):

1834 Martha
1835 William
1837 Mary
1839 Elizabeth
1841 Sarah
1842 Hannah
1844 Alfred
1846 Elizabeth
1848 Tryphena (yes, really)
1850 Abraham (my gg grandfather)
1852 Harriet
1854 Sarah Ann

Confusingly, this Betty's parents are James Deacon and Sarah - does anyone know which (if any) James and Sarah mentioned above this is?

They have a Mary Stanmore aged 80 living with them in the 1841 census, so it's possible that her mother is a Sarah Stanmore, I'm not finding too much about that name though.

[Sloe Gin]

At the moment I'm not completely ruling out this James and Sarah as parents of Betty.
The parishes of Blewbury and East Ilsley are contiguous.
Betty's parents married in Blewbury in May 1809
https://www.familysearch.org/ark:/61903/1:1:NJFL-357

We haven't found the first marriage for James born 1787, and we know his first wife was Sarah.
First baptism in Ilsley for them is 1815, but it is not impossible that they could have had more children elsewhere between Betty and William.

Sarah Stanmore was born in 1791 which matches the age at death of the East Ilsley Sarah.

Deacon, James          
Gardener.  5 boys, 3 girls. Very decent character, works hard for his family.

Bpt. 15 Apr 1787, s/o William & Elizabeth.  Married (1) Sarah, (2) Hannah Binham (b. Mixbury) 18 Feb 1849.  Bd. 20 Jun 1874 aged 87.
Sarah was bd. 18 Aug 1840 aged 49.

Children of James (1787) & Sarah
1815  William
1817  James
1819  Martha
1821  Ann
1824  Thomas
1826  Henry
1829  Jesse
1833  Amos

[Frank Toms]

Thanks, I'll pencil some of that in - if it's incorrect it's not the end of the world, I doubt I'll be tracing those people's descendants back down the tree again.

I did notice the Deacon's tendency to marry cousins - one couple gave their daughter the middle name Deacon, she ended up marrying her cousin and became Camilla Deacon Deacon!

And I ordered the Drunken Worthless Creature booklet, if I can find a couple of my mother's ancestors in there she'll be tickled.

[Sloe Gin]

Yes, if this is the case it means that Jacob and Betty were first cousins. 
It would be good to have a look at the Blewbury parish register.

'A Drunken Worthless Creature' is quite entertaining  It includes a numbered map of the village, so that you can see where everyone lived too.