Thanks ,
I thought the web parts must be able to deal with long field names. I think I know what went wrong. I shortened the field names in SharePoint but noticed that these had not been pulling through into the easy edit so when I selected a field (the new name) in the CAML filter the XML still showed the old field name. To resolve I dumped all the display fields by deleting the XML and then reimporting via ezedit.
Seems to work even though in the field names are truncated in xml.
Have yet to apply it to a whole form so not out of the woods yet.
Thanks again for your support,
Richard