[Phil G4SPZ]

G'day both, and wow! Thanks for all the info and for the superb adverts. My iron's the same, but clearly the transformer is not the original National model, although it is double-wound and the secondary is earth-free. It looks like the low voltage wiring is not original, either. I wonder which company imported these and sold them in the UK? I have no idea how it got here.

I don't think I'd use it on sensitive circuits, but last night I used it to solder a wire direct to a metal chassis and it worked admirably. I did discover that by pressing the switch a bit harder, the power can be increased to about 130 Watts. I've not tried it on a car battery - 6 volt, obviously - but it should work off a decent SLA battery capable of giving 20 amps plus.

Fascinating! Thanks again.