For a novel that is so much about civilisation and its various limitations, this is a very interesting question. Firstly, it is clear that the officer, from his physical appearance, with his "white drill, epaulettes" and a "row of gilt buttons down the front of a uniform," represents the order and structure of civilisation that the boys have lacked on their isolated island. There is a deliberate contrast between the smartness of the naval soldier and the way that the boys are described as the narrative voice shifts to looking at the boys from the perspective of the naval officer:
A semicircle of little boys, their bodies streaked with coloured clay, sharp sticks in their hands, were standing on the beach making no noise at all.
The naval officer then firstly acts as a symbolic marker to show how far the boys have fallen from the heights of civilisation. It is clear too from what he says that he has not yet learnt the lesson that Ralph and the other boys have learnt, concerning the "end of innocence." He thinks what the boys were doing was "fun and games" and then expresses disappointment in the boys' inability to "put up a better show" in the way that they coped with being on the island.
Yet, at the same time, the way in which the naval officer is described with his "revolver" and also the ship with its "sub-machine gun" ironically identifies that the so-called "civilised" world that the boys are returning to is just as violent and bloody as their savage primitive world. This reinforces the central message of Golding as he demonstrates the way in which civilisation acts as nothing more than a very thin veneer that only just covers the barbaric reality of human nature.