If it's so marvellous to be in the EU, why is the full negative truth about it always being so deliberately concealed? As you say:
there is massive support for continued membership of the EU within the political classes (and the media).
But this political & media support comes from another source hiding behind them. This is those who finance the politicians, who as far as the Tories, Liberal wing of the Lib-Dems, & some too of New Labour's main proponents are concerned, all know each other socially - or know similar kinds of people as those who dominate big business, The City, local government, much of the trendy media (especially broadcasting), well-meaning NGOs, higher education, & alumni of private schools etc etc.
Of this large group of influential people in Britain, many personally benefit from the UK's EU membership, & "have the ear" of all but the extreme left. This is "the establishment" that always seems so perfectly British, & usually is persuasively so. For example, they might well say condescendingly: "the EU is so good for Britain, & people who think otherwise must be miss-guided trouble-makers". So the 1st choice the establishment offers the rest of us is to call on us to admire their (ie the establishment's) actions & choices. But if us masses don't like the establishment's offerings, then they nonetheless carry on - but instead use deception to conceal the truth from us the public, while continuing on a bit more discretely but in a similar vein as they were before.Watchet