>So my question now is how do I prevent the parent class rendering it's own >script stuff (although admittedly this is now really only a cosmetic issue)

Attempting to answer my own question here in case anyone's interested..

The native script entries ARE added as attributes to the HTMLTextWriter by (in this case) the RenderUpLevelPath() method. The only way I can see after that to prevent them getting into the output stream would be to sub-class the HTMLTextWriter and override the OnAttributeRender(). This is beginning to look seriously like having to use a sledge hammer to crack a nut. A RemoveAttribute() method would be useful...

Still hoping someone may suggest an alternative...
Viv