Pity the poor politicians. Granite, Northern Rock’s offshore vehicle for mortgage funding, is back. But happily for them, not for long.

Granite loomed large in a confused parliamentary debate back in February, just after the shock nationalisation of the Rock. It was the “mystery firm” (not that mysterious, since its 400-page prospectus is a public document, albeit a, er, challenging read), whose voracious appetite for the Rock’s highest-quality mortgages would leave the taxpayer holding on to the “rubbish” (actually, Granite’s home loans have shown growing arrears, just like the Rock’s). In a parliamentary Punch-and-Judy incident Gordon Brown was accused by David Cameron of having shown “less openness than Fidel Castro”.