The rustiness of the long distance bolt

Thought I'd get the head off the thermostat today. As with almost everything on a 49 year-old car, instead of taking five minutes, it's going to take a while. Not only have two of the Allen bolts sheared off, but the jubilee clips on the hoses are rusted solid. So I've cleaned up the two bolts that came out intact and have replaced them so that the car is drivable, and I will leave the housing alone until I have all the parts I need to make a proper job of it.

Then it started to rain, so this evening I'll mostly be reorganising my house into something approaching a home, albeit one smelling of petrol and oil. Just one more coffee should do it...