This problem came up on the thread of Member's photographs, but I let it slide until now. Please see this thread as an example. In the first post, the User has included a photograph, using the format " {attach}number{/attach} ", which I can see if I use the "Reply with quote" button. On my display, there is no picture shown.
On the other thread where this problem was mentioned, users in the US said they could see the pictures, yet Will Northcote and I (both in the UK) could not. That may not be the relevant factor, but it might be a red herring (I hope Anders is reading this one ).
I am using Firefox 25.0.1