The director of the Richard Nixon library says that the conversation Jeb Magruder claims to have overheard did not occur. Or at least, Nixon's daily diary shows no record of him having talked with John Ehrlichman the day that Magruder says he eavesdropped on them discussing the Watergate break-in.
This is one of those "we'll probably never know" arguments. On the one hand, you have these records of Nixon's daily diary. On the other hand, those records probably are not complete and could even have been scrubbed of incriminating meetings. On the one hand, the call detailed by Magruder sounds awfully pat and you have to wonder why he sat on this info for so long. On the other hand, Magruder is a Presbyterian minister now with no visible reason to lie.
Boy, I wish they'd been able to restore that eighteen-and-a-half minute gap. It was in what was probably the first conversation Nixon had with H.R. Haldeman after the burglars were caught and Haldeman's notes said they'd discussed the news reports of the break-in. Maybe someday, someone will develop a way to "unerase" that tape.