As he was dead by 1851 it's going to be difficult to prove one way or the other.
If you put Thomas Garvey into IGI with father John the only one it comes up with is the Thomas in Coventry.
In 1841 Thomas says be was born outside of the County.
There is no Thomas Garvey born Warwickshire appearing in the census.
His 2 children are listed as Mary & John,after his parents possibly.
All circumstantial but it seems he's the right one.
jim
Edit:
The NBI has a death for Thomas Garvey/Feb.1849 aged 29/Coventry
The NBI covers Olney up to 1851 & he isn't listed there.
Maybe he died in Olney but was buried in Coventry or was in Coventry visiting when he died.
burial date;Feb.18/1849/London Rd.Civic Cemetery.
The BMSGH hold fiches & books which can be purchased which may give additional information,whether these are monumental inscriptions is unclear but here's the link:
http://www.bmsgh.org/bookshop/warw/wa_c.htmlIt looks like Parents John & Mary died 1833 & 4 resp.does his marriage list his father as deceased?