i Editor's Letter: Where should spy chiefs draw the line? In Britain, spying remains one of our world-class disciplines. UK spooks are respected and feared by rivals and friends. In two weeks, for the first time, our spy chiefs will give evidence in public. The heads of MI5, MI6 and GCHQ will appear before the inquiry into oversight of intelligence and mass surveillance - their testimony broadcast online with a short time delay. Where, ethically, should spies draw the line, when it comes to vacuuming up the minutiae of our lives? Once you have the ability to collect this data (legally or illegally), and the knowledge that a tiny proportion of it can prevent atrocity, or swing a trade deal, are you obliged to mine away? MI5"s director-general Andrew Parker tried recently to reassure a mistrustful public about the degree of intrusion, saying: "Being on our radar does not necessarily mean being under our microscope." How about the dozens of world leaders the US is alleged to have been monitoring? Page 4. Some of the international anger at America's vast spying programme is confected, and half the crime is getting caught. Everyone's at it, or is trying. The French outrage is especially hypocritical, given their history of trade espionage. But the damage goes beyond dented prestige: Brazil's President cancelled her state visit and trade talks, and now the European Parliament has voted to suspend data sharing with the US, threatening trade and security ties. Damage to key relationships is reparable, but at a cost. As for world leaders, "it's a pretty good rule of thumb," advises the ex-chair of Britain's Joint Intelligence Committee, Sir Rodric Braithwaite, "that if you don't want people to listen to what you're saying, you shouldn't use a telephone or send an email." Anyway, if someone over at Cheltenham is dipping into my documents drive... if you wouldn't mind tapping out Saturday's Letter from the Editor - let's say about 250 words by 8pm - that would be appreciated.