This 1779 death seems to be of a different Robert Hampton than the one you mentioned.
Will
HAMPTON, Robert 1779-1 Lon E d 0106396

1779-1 E d HAMPTON Robert [bur lon 17790114] d 14 jan;4 ch wm thos isable margt, robert had mar set;,wm thos isable off island;thos quine h/o margt;pledges ph moore + ph stole;inv + sale

The IGI which is often inaccurate notes a death

11 OCT 1754
Will
HAMPTON, Robert 1754-3 Bra E w 0106381