which

[tkacka15]

"Indeed, if the Bank of England’s chief economist, Andy Haldane, is worth listening to – which he almost invariably is – Greece’s travails are merely one part of the long-running financial and economic crisis that has rippled around the world since the US investment bank Lehman Brothers collapsed seven years ago." (From The Guardian.)

What is the antecedent of the relative pronoun "which" in which he almost invariably is in the above sentence?

Thank you.

 

[Barb_D]

Worth listening to
He is almost invariably worth listening to.