Susan, thanks for the tip re the clothes pegs. I'll definitely keep it in mind.
What I really need to do is take the Graflex apart and give it a good service. Other than the lens itself all of the other optics bits (glass and mirror etc.) are horribly dirty and it makes focussing really hard. The tracks need oiling and there are a load of screws that could do with replacing. I'm just concerned that once I take the thing apart I'll have springs that have been in place since 1930 suddenly freeing themselves and flying across the room never to be found again

so I'm loathe to start, but I really need to get this beast sorted if I'm going to get anything other than test shots out of it.
For instance I had no real clue whether any of the photos posted above would be in focus or not before I saw the over-exposed positives. In the end they were OK, which leads me to believe that there's a greater DOF at f4.5 than it appears through the viewfinder, but boy does it make composing a shot difficult and time-consuming.