This "silent majority" are always pretty quiet, aren't they? In fact, they were even silent during this year's general election when the Conservatives couldn't even garner a majority when presented with a massive open goal - the economy struggling, and an unpopular PM.
"Read somewhere"? Any chance of a source for this rumour? I've tried Googling but the only reports I can find seem to indicate the problem is with non-UK students defaulting, or problems with the collection process.
This report indicates £285M total unpaid debt (out of a loan book of £2.79 billion [2005/6,
source]) but doesn't break down the reasons.
My maths isn't great (I went to a crap university) but I don't make that 70%.