Fact: I started reading the newspaper diligently while working on my first book, The Chosen, and subconsciously wrote “lead” instead of “led”. Why? Because I saw it everywhere. I knew it was wrong but I still had to triple check that “led” was indeed a word because I barely see it used anymore.
According to Fowler’s Modern English Usage, the rule pertaining to lead, led is as follows:
The verb meaning “to go in front” is, of course, pronounced /li:d/ and its past tense is led, pronounced /led/. Incorrect use: His idea was the one that lead to the solution of the mascara mystery — Chicago Sun-Times, 1990. The chemical element lead, pronounced /led/, is of quite separate origin; the associated verb and its parts (leaded, leaden, etc.) all have /led/ as their first syllable.
And there you have it. Unless you’re talking about the element or you’re writing in the present tense, don’t use lead. If I see you make this mistake, I’ll sic Fowler on you and trust me, it won’t be pretty.