The enumerators of the England 1841 census were instructed to round down ages of people over 15 to the nearest five. It wasn't always done, though. Furthermore, I have seen plenty of examples of ages out by seven or eight years. Maybe they weren't always that good at arithmetic.
Not only that, but the enumerators could only record what they were told. There was no checking.
So, while there was a specific census date, the recorded age could easily be out by five years or more.
As for Matilda herself, Ancestry has an image (source citation is <ref>
'''Marriage''':
"London, England, Church of England Marriages and Banns, 1754-1938"<br/>
London Metropolitan Archives; London, England, UK; London Church of England Parish Registers; Reference Number: P88/ALL1/028<br/>
{{Ancestry Sharing|12842920|7b22746f6b656e223a2241736f6e6858544e6f3643396c4c476d4254443865594761566d6c2f4c765259725a6c64317a3447396a453d222c22746f6b656e5f76657273696f6e223a225632227d}} - {{Ancestry Record|1623|7095487}} (accessed 18 April 2024)<br/>
Matilda Pritchard marriage to Matthew Conway on 27 Jun 1841 in All Saints, Poplar: East India Dock Road, Tower Hamlets, England.
</ref>) of the marriage record. It tells us that Matilda was the daughter of James Pritchard, a cabinet maker. The marriage took place on 27 June 1841 at All Saints church, Poplar. Witnesses were Benjamin Peatt and C F T Maundrell (I'm not sure I've got either surname correct).
There is always the possibility that Matilda did not know her age, or else perhaps even lied about it for some reason (such as not wanting to be too much older than her husband) and never corrected it.
