According to The Ring (August 2003) the featherweight's loss to Miguel Matthews was a result of a cut caused by a headbutt: "Harrison was cut by a clash of heads, and, under English rules, lost on a TKO in a fight that would have been declared a no-contest in America." (Doogan 48)
Don't know if this fight deserves a comment, but seeing that Mighty Miguel had a modest 13-80-11 record, it'd probably help put the "knockout" in a bit of perspective.