Again - thanks for your comment/squee! The idea of Jeremy Brett & Alan Rickman, acting as Holmes and Snape, in the same film, makes my brain melt out of my ears. Between them, they would chew up every other character and the scenery and spit them out..... guhh.... sad that we lost Brett.
I wasn't so much hinting at the lunch location, as trying to hint that when Snape Legillimised Holmes, he saw that Holmes already suspected where the watch was. Watson didn't know, of course, and Holmes couldn't risk him knowing but Holmes knew that Snape was unlikely to give anything away.
I wanted to suggest that Watson was a double bait, that with Snape's tracking and protection charm on him, he was being let loose in London in order to draw Moriarty out of hiding, Moriarty snapped up the bait thinking he was drawing Holmes in, when in fact he was on a line himself. Like Voldie, he over-reached himself and underestimated Harry in particular, which was Snape & Holmes intention when they sent Harry out alone. Harry was fairly safe, because Mortiary would regard him as a messenger only - and a 19th century gentleman wouldn't dream of killing a humble messenger, it would have been very bad form - and because he was excellent at defensive magic and he had his super-wand anyway. He would then be in a position to protect Watson, and Moriarty would disregard him once Holmes appeared. The arrival of the Prewetts and their friends was meant to mirror the arrival of the house elves and centaurs in DH; allies who were mentioned earlier, not taken too much notice of, and who could arrive in the nick of time to save the day. The presence of the watch twice in the same time was something that I hoped was both obvious and yet hidden - if you go back in time ten years, you can meet yourself, so if an ancient artifact carried someone back in time, it was bound to be able to meet itself there. Holmes knew that, after their researches in the library, and he concentrated his efforts on finding the correct version of the watch while getting everyone else running round after the other version, basically because he was like that! He was a Slytherin to the core. I was rather pleased with the way he misled Snape - he never actually lied, he just let Snape believe that Harry had died and hoped that Snape's reaction would reveal his true feelings to Harry, which it did, and Harry being a Gryffindor would seize the opportunity. Heh, glad it all worked out!