Pink Floyd - signed The Wall

Hello,
Few years ago i bought The Wall signed album.
On one side there is 3 signatures by:
- David Gilmour
- Roger Waters
- Gerald Scarfe (sleeve design/animation)

On the back there is one more signature - but don't know whose?
Any idea from audiophiles here?
link to images of the album:

http://imageshack.us/g/1/10489794/

Also, i was thinking about selling it.... or should i keep it? No idea about LP quality, dont have analog player in my system...

Thanks a lot
Stan