Rewards: Pounds: 900 (+250), EXP: 700 (+250), Extra: Firearms - M1877 "Lightning"
Challenges: 1. Burn the counterfeit money. 2. Let the civilians into the Bank.
Approach Abberline (with Evie) to start this memory. Follow him, then continue onwards and scan the area up ahead for the counterfeiter. Move behind one of the pillars and stay about ten meters away from him. He'll soon get onto a carriage on the other side of the exchange, so hop into a carriage yourself and continue tailing him, but keep enough distance (the game will warn you when you get too close).
When the counterfeiter exits the carriage, climb to the buildings to your left and use the rope launcher to reach the top of the building to the right. Alternatively you can assassinate the carriage driver and just climb to the top of this building. Scan the area with Eagle Vision. You'll see the counterfeiter along with three thugs near a burning barrel. Ignore them. Indeed, go to the other (south) side of the building and drop down. (Remember you can check the tiny white arrow on the edge of your minimap to learn what direction is north). There's an open window here.
If you've scanned the area you'll notice a watcher standing with her back towards you i the hallway, and there's a brute patrolling here, coming up the nearby stairs. Depending on where the brute is currently located, either kill him first, or the watcher, then hide as the brute shows up. In any case, in this room you can find the counterfeit money, which you must burn to complete the challenge. Head downstairs and kill the enemy here, then collect the printing plates. You can now exit the building via the same window on the floor above, and head to the Bank of England.
In order to complete the challenge, assassinate the officer blocking the crowd and wait inside while watching the mass of people drip inside. You'll probably attract some attention, so defeat the remaining officers, either by approaching them from the back and gently putting them out, or killing them. In any case, the plates can be put back by going through the main lobby and then turning right. To escape the area, simply exit via the nearby open window, or the main entrance again. Speak with Abberline to complete the memory.