Update:
So I called the building manager to let him know there was a theft and he is as shocked as me. We're chatting and asks for a description of the bike, just in case. So I tell him, 'huge frame, silver, Trek, silver pedals' and leave it at that.
Thirty minutes later he calls me back - he thinks he has found my bike! He says there has been one matching those descriptions parked in a fire escape for the last two weeks that he thought was weird (but left a note on it). He says he'll put it in the storeroom for me so I can ID it after work.
So I leave the office early, arrange to meet him and he shows me.....my bike!!

. All accessories are still there, including pump and lights too

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Piecing together the story, it seems some louts tailgated someone into the underground parking and made a bee line for the most impressive looking bikes (not kiddies bikes/ bangers) and then decided to escape by using the fire escape. Luckily for me, the fire escape is also used by the caretaker to keep all the empty wheelie garbage bins - about 20 in a passage that is hardly wider then the bins themselves. So the thieves got up the stairs and found they couldnt get my bike between the bins and the wall, so left it there! Why, because the fire escape is a one way door 👍.
Morale of the story: buy a big mofo D-lock and have wide handlebars

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I'm just stoked to have it back, all in one piece

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