There's another four Secrets to ferret out in the borough of Lambeth.
Secret #19 - Lambeth
The Secret is to the north of Lambeth Palace.
Either scale the palace and drop down into the gardens below, or make your way around the side via the street and jump over the wall.
Go straight past the fountain to the north end of the gardens and you'll spot a tree stump with the music box perched on top.
Secret #05 - Lambeth
The next Secret is to the northeast of the Lambeth Asylum.
You can see the building you need to head to from the Lambeth Asylum viewpoint. It's the small church on the corner.
Leave the Asylum grounds, nip across the road and head right to get to the church.
Climb up to the parapet to find the music box on the roof.
Secret #06 - Lambeth
This Secret is in the southwestern corner of the borough.
Make your way to the railway bridge that lies south of Lambeth Palace.
Drop down to street level and head straight over the bridge.
As you cross, look down to the left and you'll see a jetty below.
Drop down and hop over the water to the alley between the houses.
The music box is resting on a coil of rope here.
Secret #08 - Lambeth
This one's nice and easy - you'll find it right on top of the northeastern viewpoint.
Get yourself to the viewpoint in the northeastern corner of the borough and you'll find the music box just lying up here for the taking.