Series 9 Episode 6 discussion

[Naivety]

'John' is the most common name in this country. If you were going to make up a name on the spur of the moment, you would probably pick it. What shocked me most was that when Malcolm said it, Lucas put his hand on his gun. This may have alerted Malcolm to the fact that the visit wasn't real and so he gave him a fake file.

Incidentally, how did Lucas know to go to Malcolm's home address to fetch it? Did I miss something?