Missing - yellow and red cards. One careless owner

In the crunch match between Wateringbury U18s and Sittingbourne Lions on Sunday,

the referee got into a bit of a quandary by losing his cards at half time. In fact they were in his bag, but he thought they'd fallen out of his pocket. In the second half, he booked 2 players, writing their names down on a scrap of paper, but he was unable to show them a yellow card. He's a friend so I won't name and shame him, but it threw up an interesting point of law. Can he book a player without showing him a card? Can the player appeal against the booking? As far as I can can see the Laws of the Game don't help us specifically other than saying, "a player is cautioned and shown the yellow cards if he commits ..." in its introduction to the section on sanctions. Anyway Graham Poll and his assistants, in this picture I took at the World Cup last year, could have done with losing his yellow card. At least the ref on Sunday didn't show it three times!