I can do this in desktop - see arcgis 10.0 - How can a place a point symbol on the center of a polygon? - Geographic Information Systems Stack Exchange
But this will not go over to AGS, it moans about the symbology not being supported.
The ability to do this is important as for a map that is zoomed out to our full district it is hard/impossible to see small polygon features. Having a symbol in the middle of set point size is a good way around tis.
Any ideas how to achieve this in AGS?
Answer - sort of.
I set a label on this layer. I used a Shield Type label, but changed from a shield to the symbol I wanted. I picked a random field for the lable and set the font colout to "no colour" this seems to have worked - the only issue is that this centre marker isn't then shown as part of the legend, so open to better suggestions.