At the conclusion of Golding's novel, Lord of the Flies, there are implications the British officer is appalled that the boys who appear to have degenerated into savages have not made a "good show" and remained more civilized. For traditionally, decorum is held in high regard by the British (One does not display weakness). Remembering that the boys, who are Australian--not English--are members of the English Commonwealth, the officer makes this remark as he is also somewhat embarrassed, as a fellow Brit, by what he perceives as their breakdown.
His remark that chides the boys for not having been civilized and overcome adversity as the English schoolboys did in the Victorian novel, The Coral Island, is quite ironic in light of the fact that he wears a military uniform and is from a warship which engages in anything but "civilized" actions. Golding's juxtaposition of these contrasts points to the inherent evil in man, an evil that is present even in the "deus ex machina" that saves Ralph from certain death at the hands of the savages.
To me, what the officer is implying is that the boys have not been able to be as civilized as English people ought to be. He is implying that there is a certain level of dignity that English people ought to be able to maintain and that the boys have fallen short of that level. So he is implying that they have failed -- they have not acted well enough to really deserve to be English.
I think that what we are seeing here is the idea that English people gained their empire by being superior to the people they conquered. The officer is saying that these boys have not lived up to that ideal -- they are not superior because they have not made civilization out of chaos.