"I've heard that SAA are blaming it on poor star alliance connectivity in London reducing loads" That'll be the demise of bmi's LHR operation then. But the only useful connections that they've lost from this would be MAN, EDI, ABZ, BHD and DUB (I can't see why one would want to route via LHR for any other Star Alliance connections).
Funny old thing, but Virgin manage without any alliance connections. What are they doing right that SAA aren't?? (That was a rhetorical question, by the way!)