If so this seem to be the simplest approach for importing data from other sources because I can extract data from the old forum without problem, the difficultly is getting an import into discourse.
So I ended up writing one myself, expect this is of most use to other Java developers moving relatively small forums to Discourse from another forum. In my case i was importing from JForum but the tool is not JForum specific it just works from .csv files.
https://meta.discourse.org/t/discoursetransfer-simple-java-tool-for-import/138800