Who's autograph is this with Guy Gibson's?

Hi there,

We are currently auctioning a few Guy Gibson autographs. One is a signed photograph of a Lancaster Bomber. It is also signed by someone else but it is unknown who.

I don't think I'm allowed to post a link but you can find the photo by searching Guy Gibson on the PFC Auctions website (its lot 137). There's more information there that might be helpful.

If you have any ideas please let me know!

Thanks.