I think your assumption that it's a printed signature is probably the right one.
Even though you can see it through the page - that's possibly just to do with printing and paper quality of the time.
If you Google "Thomas Hood signature" in Google images, the first three results are the same as yours - this one shows it from a 1906 edition and to me it looks absolutely identical.
The only real way to find out for sure is to take it to an antiquarian book dealer and ask their advice - they might be able to tell you straight away, or point you in the right direction. I would say it was impossible to verify its authenticity - or otherwise - from a computer screen.