There may be an easier way
From Fallen London Wiki
| A player-created Guide is available for this content: On a Heist (Guide) |
| Spoiler warning! This page contains details about Fallen London Actions. |
From: A Troublesome Lock
If you remember correctly...
Unlocked with 
1 x Inside Information
Success
Aha!
A loose tile under that knock-off statuette of a drooping cherub. There's the key. The cherub regards you reproachfully.
You've gained 2 x The Burglar's Progress
You've lost 1 x Inside Information
