Any autograph increases in value if the person is famous and deceased - so if you have Ritchie Edwards's signature as well as the rest of the band, it is a collectable item. Stick it on ebay and see what happens.
Definitely signed by all of them. I got it years back when I was at sixth form college. I saw them at the Aldershot West End Centre along with about 25 other people just after they released their first single (when they were a bit punky). I wrote to them afterwards asking if they'ed come and play my college. They said no but sent me the photo to say thanks for asking. sft42 - would have said yes to the happy meal but found a old can of oxtail soup at the back of the cupboard :)