After going out of the resistance main headquarters turn left  and cross the stone bridge to the other side .
On the right you should see a crane . Right below it, beside the river shore, you will find a sewer entrance. Inside, turn right and at the end of the path you will find the silver key .
In order to get the next one, return to the bar by the resistance main headquarters. Exit it, keep moving right until you reach a big factory with an open door  by the pier. Inside the building, go up the stairs on the left and a cloud of steam will block your path . To get rid of it, you just need to pull the nearby lever. Afterwards push the one on the right and then one the left once again. Afterwards use the first mechanism again and pick up the silver key.
Head to Nigel Ferrer's hideout, to where you went during "Kidnapped". After defeating the group of bandits , jump down and turn right on the first intersection .
Pay close attention to the left wall. You should see a boarded passage there . Destroy the planks with any spell  and pick up the silver key .
Once you become the king of Albion, head to the bridge with the view over the docks  and turn into the street on the left .
Behind the steel gate you should see a warehouse entrance. Go inside and climb up the stairs on the left . At the top you will find an elevator and inside a silver key .