The earliest it could possibly have been is 1400, about two hundred years after the Old English period.
I'll modernize:
"Man, here you may see entombed a man of honest fame come home to earth who in life bore the name of William Cantrell - a gentleman by birth, in life, and in office and degree - now wrapped in clay. Think then, O man, what shall become of you. This William Cantrell was the owner, along with others, of an estate placed in trust. [He was] well regarded for his virtuous life, wise sorertrev and lvste [this is obscure and I have a couple of possible interpretations] of all the revenues of that mighty prince, the late Thomas Duke of Norfolk, formerly called of high estate [considered to be very powerful]."
Thomas de Mowbray, the first Duke of Norfolk, was stripped of his lands and title in 1399 - if he was "late" as of this inscription, it can only be 1400 at the earliest if legitimate.
The text doesn't refer to Thomas de Mowbray. It refers to a much later Duke of Norfolk. In the 16th Century, there were no less than three Thomas Howards who were Dukes of Norfolk. There were two more Thomas Dukes of Nofolk in the 17th century, but my guess is that this is 16th century.
I was thinking that the ‘s’ in “sorertrev” might be an ‘f’, since they sometimes looked alike. For some reason I think ‘lvste’ might’ve been ‘trust.’ I’m no expert though.