Hi
If you subtract 1785 from 1810, you get 25
If you subtract 1789 from 1810,you get 21
This looks suspiciously like the IGI 'formula' for 'estimated' ages that a person would be at the time of a certain event that they (IGI) have documentation records of.
I can't get into the IGI at the mo - but I'm picking the 1810 marriage is a submission and on it it also says Diana b 1789 Poole and John b 1785 Poole?
If so, I'd bet my hat, that this submission is based soley on the extracted Christening record of son William in 1811. IGI then neatly estimate:
1) The parents were married before the birth and this would be
the year before the baby was born

2) Average age at marriage for father = 25 (so born abt 1785)
3) Average age at marriage for mother = 21 (so born abt 1789)
4) And since the baby was born in Poole, then probably the
parents were married there, and possibly from there ( <of
Poole> )
These 'estimates' may sometimes work out about right. But many do not - I remember one case years ago, when the couple in question were eventually proved to be in their 40's when they married and had one last gasp child. They were born way before the IGI assumed they were!
I'd agree though, that VINEY may be an important clue.
Cheers
AMBLY