Perhaps the person who posted the image on Findagrave confused the two Walter Blounts?
Evidently - and they must have lifted the photo from somewhere else as they clearly haven't visited the church where they claim it was taken. Nor, it seems, are they aware of the significance of Leicester in the instructions in Sir Walter's will. (I admit that at first I too prioritised 'Newark' over 'Leicester', though I had hoped to find a copy of the will in order to make sure of what it actually said.)
It appears you can submit corrections at Findagrave, though you need an account to do so.
I wonder if there is any evidence anywhere to say that Sir Walter Blount was buried at Leicester?
No parish registers at that date, and as has been pointed out, the church is no longer there. There are articles about Sir Walter at Wikipedia (beware - the article there on St Mary's Newark says he was buried there!) and the Dictionary of National Biography (which is generally regarded as pretty authoritative); these might lead to other sources, but I don't know what they would be. Ideally you'd want to find some contemporary chronicles; or I wonder - might his widow have left a will in which she asked to be buried "alongside my husband at...."?
https://en.wikipedia.org/wiki/Walter_Blount_(soldier)
https://en.wikisource.org/wiki/Blount,_Walter_(d.1403)_(DNB00)
The DNB link here is to an older out-of-copyright edition. I can access the latest one through my public library card, and it adds a bit more:
- Sir Walter was entrusted with the care and tutelage of the young Prince Thomas
- Sancha Blount lived until 1418 or 1419 as a pensioner of the crown and was buried beside him
- Prince Thomas set aside 1000 marks for the erection of a splendid Blount family chantry at St Mary's.
As sources, it mentions Parliamentary (Commons) and Chancery records, and the following volumes:
N. H. Nicolas, ed.,
The Scrope and Grosvenor controversy, 2 vols. (privately printed, London, 1832)
S. Walker,
The Lancastrian affinity, 1361–1399 (1990)
A. Croke,
The genealogical history of the Croke family, 2 vols. (1823)
R. Somerville,
History of the duchy of Lancaster, 1265–1603 (1953)
Just a few things to get your teeth into....