> a lot on the forums maybe) are the missing pictures.

<http://underground-history.co.uk/robots.txt> says:
Disallow: /images/
You will have to override robots

> I am not sure what the problem could be, since I am
> more the pure HTML-guy. I have no idea PHP works. 
PHP is irrevelent, you can only get the html output from the public side of a
web server.