1d Black (plate 3), clearly cancelled by two different red Maltese Crosses on a cover to Liverpool.
Quite possibly a postal fraud. It also may be that, when arriving at Liverpool, although already lightly cancelled with a darkish mx, it was deemed to be insufficiently obliterated and given an extra strike to make sure.
Cover also bears Lane-Delph undated circle on front.
Rockoff and Jackson Vol 3, page 402.