Gerri Peev: One in three MPs on the fiddle?

THANK God for Ken Clarke. The Tory High Command had been reminding hacks to get up early to watch the Shadow Business Secretary on the Andrew Marr Show today. This triggered suspicion that this time he would be disappointingly gaffe-free and on-message. Especially after his last appearance during which his words on inheritance tax cuts (that it was an "aspiration" not a pledge) triggered coronaries at Conservative HQ and in the grassroots membership.
This time, though, after a bland start, he came out with this gem on MPs and their expenses:
“We have an exaggerated public view that they are all thieves, they are all rogues, they are all lining their own pockets.
“Two thirds of them, I am quite sure, are doing nothing improper at all," he said, before hastily adding "At least two thirds I hope".
Is Mr Clarke saying up to one in three MPs is a crook?