Copyright notices on GPL'ed software

[Dave (from the UK)]

There is a chess software program package 'scid'

http://scid.sourceforge.net/

which was primarily developed by one author. He license this under the 
GPL. Most/all of the source files have a copyright notice similar to this:


Part of:    Scid (Shane's Chess Information Database)
Notice:     Copyright (c) 1999  Shane Hudson.  All rights reserved.
Author:     Shane Hudson (sgh@users.sourceforge.net)

Shane has unfortunately stopped developing this, and does not seem to be 
contactable.

I decided to take on further development of the project, so created a 
new project on Sourceforge

http://chessdb.sourceforge.net/

for a new chess program 'ChessDB' for which 99.9% of the code is the 
code from Scid, with minor changes here and there.

What copyright notices should be left and/or added to the source.

Previously, the 'About' box in this graphical software showed his name 
and copyright. Should this be removed (he has not in any way agreed to 
be part of the new project, left in place, or what else?

I've no reason to wish to claim his code, and I understand he has in the 
past not been happy with people medalling with his code, but it is 
licensed under the GPL.

Not sure of the best thing to do, to protect the code from someone using 
it in closed source software, giving Shane credit for the work on which 
this is based etc.

Any advice.
--
Dave (from the UK)

Please note my email address changes periodically to avoid spam.
It is always of the form: month-year@southminster-branch-line.org.uk
Hitting reply will work for a few months only - later set it manually.

http://witm.sourceforge.net/ (Web based Mathematica front end)