Who said "It is difficult to think how much lower our collective reputation might sink" and when?
It was Frank Field, in January 2008. The quote is from a BBC report at the time. (Hat tip to Liberal Vision for that one.) The occasion was the outing of Derek Conway's little scam. For more details of that, go to A Man For All Sleazons, and scroll down (you'll have to scroll a fair way to get past all the other Tory crooks.