Marcus Agius said "the buck stops with me," in resigning after the interest-rate rigging scandal. But the buck shouldn't stop with the Barclays chairman. It is appropriate that Mr. Agius has fallen on his sword because he hasn't acted as a strong counterweight to chief executive Bob Diamond. But the chief executive was responsible for the culture at the Barclays Capital investment banking arm, where the manipulation took place, as well as other lapses.
Mr. Diamond has done an extraordinary job expanding BarCap. But it is hard to believe he is the right person to clean it up. In a BBC lecture last year, he said "the evidence of culture is how people behave when no one is watching."
Not only did several Barclays traders behave badly when he was not watching; he himself was somehow involved in a chain of discussions which led to the bank submitting an artificially low interest rate to disguise an appearance of vulnerability during the credit crisis.
The interest-rate rigging scandal isn't the only black mark against Mr. Diamond. He received a hefty bonus for last year despite a performance he himself acknowledged was "unacceptable." And he presided over a bank that concocted aggressive tax avoidance schemes.
Barclays may hope that the blood-letting will stop with Mr. Agius. But the scandal has a dynamic which may make this difficult. The next flashpoint will be on Wednesday, when Mr. Diamond is to appear in front of a British House of Commons committee. Given that politicians are competing with each other in anti-banker rhetoric, this will be an uncomfortable experience – even if Mr. Diamond can argue that Barclays was not alone in manipulating rates.
Beyond that, the spotlight will switch to Barclays' new chairman. Sensibly, the bank is looking both externally and internally; the main inside candidate is Michael Rake, now promoted to deputy chairman. It needs to find someone who both understands banking and is tough enough to find a replacement for Mr. Diamond.