I will personally keep and eye out for that IP address in future. Port scanning the IP address can be a good way of identifying the person if they have not taken suitable security protection such as a firewall. However. I would not recommend it as it port scanning is frowned upon by most ISP's and you could end up getting your Internet connection pulled. Normally if the ISP suspect you have been port scanning they usually issue you with a gentle warning first as some programs can port scan without the knowledge of the person in question. Hope this helps.
Those of you who have had run ins with Drachen might want to check your firewall logs for port scanning from an NTL ip from Scunthorpe and report it to NTL/Virgin. It is certainly against their TOS.