Well, after a few phone calls I'm still not sure what this torque setting should be.
My Doblo has the larger diameter discs (284mm diameter), it appears that there are 2 diameters of disc for Doblos of my vintage. The caliper bolts are M12 for the larger disc and M10 for the smaller disc.
I've been given 2 torque values, 57Nm and 105Nm, for my calipers. To me the 105Nm seems the sort of torque that would shear off the bolt. The 57Nm figure came from a reliable source, so that's what I used. It seemed pretty tight and with a dab of loctite on the bolt I'm quite sure it's going to be OK.
Cheers
Ron