A spanner if you're going to need it more than once.

Lever: A rubber jar opener or rubber stopper also works. You need to put the camera on a flat surface and use A LOT of pressure as you turn the rubber.

Shutter speed dial: 1, is there a soft touch, shutter release extender installed? If there is, it looks like a silver nut with two notches is beneath it. It's a standard thread.

It looks like it will definitely need a spanner.