There is nothing that you can realy do, apart from NEVER following any link included in any of those messages and marking those as SPAM. As you said, your address have been "scrapped" or "harvested" of the net.
The "From:" feild is ALWAYS forged. Have been the case since 1996...
Anyway, if you trace the message to it's origin, you'll get some poor soul whose computer is infected by a virus.
Final word: It's not worth the time and effort to trace the origin of those messages.
You already made a prety bad move by clicking the "unsuscribe" link, as it ONLY purpose is to validate your e-mail address, and pretend to comply with the infamous canspam act in the USA. You WILL get even MORE unsolicited e-mails now :(
It tels them that, not only there is somebody there to receive the message, but also that you actualy read the message and tend to follow links sent by total strangers.
If you read the message, there is a greater chance that you may actualy follow a buy link...
Their rentability threshold been at not even 0.00001% sale per message sent (less than 1 in 10 MILLIONS), if you buy anything you contribute in increasing the SPAM volume for everyone, worldwhide.
There is no place you can report this as the spamers who send you that junk are realy criminals and other unscrupulous entities who only want to make a quick buck by scamming the unwarys. They absolutely don't care how you feel, definitively disregard any laws, use virus infected computer abroad to send those messages,...
They probably don't reside in the UK. Are commonly related to organisation like the mafia or similar. The Rusian mafia is commonly implied. It seems that some terrorist groups or cells use that as fund raiser.
DON'T just delete those messages. Also, don't just move them to your junk folder.
If you use a webmail service, always use the "Signal as SPAM" button for those messages. In doing so, you help all other users of that service.
If you use a local application to read the mail, look for a "Mark as undesirable", "Undesirable" or similar button. It will instruct the imbeded SPAM filter about what is an unaceptable message.
Also, set it to automaticaly move marked messages and filtered messages to the junk folder. You can then quickly scan that folder to catch any false positive.
Thunderbird have a very good adaptive, trainable, SPAM filter. After a few months, it will have a success rate of about 100% at elliminating those messages.
In my case, Thunderbird's effective filtering effeciency is 100% with NO false positive over a 5 years period.
Electro, May 2011