Yes doctor : ) you've understood what I want fine. Someone gave me some parameters to try within "bevel plus" and it worked OK though I got strange anomalies when I shaded the object which I'm sure are fixable. Your idea of extruding the figure of 8 with a circle is interesting but I can't find any information about it. In the end I created two torus's / torii and positioned them to make a 3D figure of eight, boolean unioned them and smoothed the join with some teaking of the vertices with good results. Here's the flat logo and the torii which once I've rendered I'll mask within the flat logo.

https://www.behindyou.info/test/ldc/ldcFlat.gif
https://www.behindyou.info/test/ldc/ldcTorii.gif

Thanks, Edwin