Dulwich Hill Bicycle Club

My friend has an size L Giant OCR3 http://archive.giant-bicycles.com/au/03 ... model=9609 and wishes to put the seat further back than the rails currently permit.

1. Is there such a thing as an adapter that will permit the seat to go further back and are they any good.
2. What are the recommendations for a seat post with more rearwards offset.

2. Thomson Elite with setback (http://www.lhthomson.com/gallery/esb1_1280.jpg). I wanted the setback model but couldn't find that one on ebay so settled for the straight one. In retrospect I should have got the setback...