This follows his proposal that we should all display a coloured rag on the end of an idiot stick, also known as the Union Jack, on the Monarch's Birthday or some special "National" day he has hinted he would like to introduce (as long as it's not a working day -- the business interests he has catered for as Chancellor of the Exchequer wouldn't like that).
"Britishness" has become something of an obsession with him. Psychologists have suggested that it might have something to do with, being from Scotland, him being unsure of his "Britishness" and so over-compensating in the same sort of what that Hitler, an Austrian, did with "Germanness". More probably, his spin-doctors have detected that voters in England might not be too keen to vote for a party led by a dour Scotsman whose father was a Presbyterian Minister and so have told him to play up his Britishness. In other words, usual political opportunism. Or maybe he wants to steal votes as well as policies from the British National Party.
But it also serves a purpose. The capitalist class rules in the end only with the consent of the ruled class and nationalism is one of the means they use to try to con us that we have a common interest with them as against the inhabitants of other capitalist states. Brown perhaps feels that liberal and cynical attitudes have gone too far and that we need an increased dose of nationalism to keep us ideologically bound to our masters.
Whatever the reason, he has now come up with the outrageous proposal that workers who come to Britain and want to settle here should first have to undergo a spell of forced labour before being entitled to the "privileges" of being a legal subject of the British State. The Labour Party used to pose as a champion of civil liberties and the like. Not any more. They are now an openly authoritarian as well as an openly capitalist party.