Hi there Peter,
thanks for you reply. I actually sorted this myself - I was using loadcontentfromfile(), which did not databind the xml so could not use the itemdatabound() handler.
I've now moved the code to itemdatabound, and modified it to the following (in the unlikely event it's of use to anyone else):
RadMenuItem = sitemenu.FindItemByUrl(Request.Url.PathAndQuery)
item.Level > 0
'menu will only ever be one level deep
RadMenuItem = item.Parent
This seems to work fine - however I'm looking at your breadcrumb demo just now :)