Hey!

As far as I understand it, Molly was really flattered about the attention she received from Jim (although I didn't feel she was really in love with him, the 'office romance' didn't go on long enough). As for Jim, he took the opportunity to meet Sherlock at work and check out how smart he really is. Therefore he dressed up like that and gave Sherlock his number. If Sherlock had worked out somehow who Jim really was (although I have no idea how he could have known by that time, but nothing's impossible with Sherlock), he would be able to call Jim. But on the other hand there was the possibility that Sherlock would only deduce Jim's gay and tried to flirt at Sherlock by giving him his number. It was just a check - and a fun thing to do for Moriarty.

I read / heard somewhere that in one early draft of the script, this would be the only time Jim would be seen in person and that Sherlock would somehow find out it was him after Jim had left but could not find him anymore. I'm glad that's not the only scene with Jim in person, to be honest.

I agree, without the scene the whole sequence at the pool later on would have felt a little different. I still remember how I started to go "Wait a minute....!?!?" the moment I saw him at the pool. That was great!

Also, I think the scene in the lab is important because it shows us for the very first time that Sherlock isn't perfect and that there are people out there who are as clever as himself - or maybe even more clever. Jim played him. He pretended to be gay, but Sherlock didn't realize it was just pretense, he believed it and thought he'd made a clever deduction. And he completely missed 'the real' Jim.

Poor Molly!  It's so funny in this scene that Sherlock completely misses anything else he might deduce about Moriarty and picks up on "gay"!  Then just afterwards, when John tries to make deductions about the shoes, Sherlock says that he did really well apart from missing absolutely everything of importance!  Not realising that he's done just the same thing himself .

Anyway, I think it's clear that Moriarty has engineered the situation to catch Sherlock out (and it must have been complicated, because he must have had to get the IT job ... or at perhaps pretend he had it) and uses Molly to meet Sherlock, but not for the reason Sherlock thinks.  Moriarty is playing games.   It's funny that he leaves his phone number and Sherlock doesn't understand the significance of it.  I think Molly is also trying to make the point that a nice-looking guy wants to date her, and to play it cool with Sherlock, and Sherlock disillusions her.

I'd think it would more likely be the number of one of those disposable cell phones.

Exactly. I said a disposable phone so it wouldn't have been traceable, but Jim would have wanted to answer any call.

@Liberty
@Magingus

I'm convinced you've got it both right. Yes, Sherlock misses that this is in fact Moriarty, and that's very funny in retrospect when he scoffs at John for missing everything of importance. But it also shows that Moriarty, like Sherlock, is able to hide in plain sight. They truly are like each other, except for the fact that Sherlock is on the side of the angels.

I missed that completely.

I thought it was all part of the 'gay' deduction.

I thought something like this develops with time. The other clues like the underwear, the hair gel or the colored eye browns are easily done. So thats right, you could fake the nightclub eyes but in my opinion it didn't fit to the other clues. But I am not an expert in faking nightclub eyes or disguise too