Hi Iain,
If you look at the wikipedia entry you'll see all the blurb about Christina O - now owned by a family friend of the Onassis's - and available for charter, but I'm about 3d short this week so.....maybe next payday......:-))
I've seen her shown on this site as being in Chatcham docks again today (and yesterday) I posted a reply to you question but it didnt see to register - so if this comes out twice you'll know why. As for her being in Thamesport, I live by the river about 2NM from Thamesport and see all the vessels arriving and f she was one of them, I'd notice. Perhaps the confusion lies elsewhere - there is a tug based in Sheerness called 'Christine' , so perhaps her signal is being mistaken - and I dont think there'll be a que for chartering her....
I still think that the site must have been hacked, although why anyone should bother, I have no idea
Regards
Peter