According to this Eurogamer piece, Nintendo's E3 press conference will be held at 9pm PST on July 15 at the Kodak Theater in Hollywood.
This is either 4pm or 5pm BST. We're on a train in a shit internet connection, so we can't really check without ruining our loves, so we'll take a look later.
Bet it won't be as good as the Leipzig showing. Oh.