How can I take Sarah's personal effects?

You will need permission from someone at Scotland Yard.

Gregson can't give you permission, but he'll tell you who can.

If you need help getting into the Yard, see a later question.

Now all you need to do is contact Lestrade.  A bit of inside help is needed.

Have you talked to the blind man outside?

The last place a fraud should be standing is in front of the police station.

But Holmes will realize that he's not really blind.  Use that information to
learn something important about the officer at the desk.