For what it's worth, the rest of it basically tells us his regiment on the top line. "Sold" is short for Soldat, or "soldier".
Second line: "geb" = "geboren", ie born 25.9.1899 in (zu) London. "Arbeiter" literally means "worker", but most likely is "labourer".
"verst" is short for "verstorben" which means deceased. Your relative died on 2/10/18 in a Prisoner Of War Hospital (im Kriegsgefangenenlazarett) in (zu) Darmstadt.
"Infolge Darmleiden" has already been translated correctly for you by ShaunJ.
RRTB