Hi Ian, hopefully I have the right information for you this time
I'm not sure why you mention William
Did you by any chance take notes of the dates for the other two burials - William Snr and his wife Sarah?
As the brothers William & John were born to John & Sarah Dyon.
John Dyon Snr was buried 14.04.1833 aged 83
Sarah Dyon was buried 22.11.1805 aged 66 (both at St Helena's Church, Austerfield)
I also found the following:
William Dyon christened 15.09.1782 - parents John & Sarah (transcribed as Diyion)
John Dyon christened 21.06.1784 - parents John & Sarah (transcribed as Diyon)
William Dyon married Sarah Senthouse 24.03.1805
John Dyon christened 14.07.1805 - parents William & Sarah
Elizabeth Dyon christened 22.02.1818 - parents John & Betty
John Dyon christened 02.01.1820 - parents John & Betty
John Dyon buried 03.03.1820 aged 2 months
Matilda Dyon christened 22.12.1825 - parents John & Betty
Also
"Mrs Dyon who was delivered of a still born child on Friday, in consequence of the shock which she received by the afflictive event of her husband's murder, continues in a very delicate state of health"
This was reported in the paper dated Friday 29.02.1828 so I think think the date would have been the previous Friday 22.02.1828
All the above was at St Helena's Church, Austerfield.
I searched the parish registers and the IGI films and there is no record of a marriage for John & Sarah or John & Betty which is a shame (although you may have this already).
All the best, Goofy