I think I have an explanation (sort of). When I take that URL:
Code:
http://www.smle.army-cap-badges.talktalk.net/.\Anodised%20Territorial_files\0001.jpg
and change that into:
Code:
http://www.smle.army-cap-badges.talktalk.net/Anodised%20Territorial_files/0001.jpg
by making the idiot \ into / (and removing the superfluous ./ at the beginning), it loads.
And indeed, when you look into the source code of the web page:
HTML Code:
<p align="center"><img src=".\Anodised Territorial_files\0001.jpg" width="128" Height="155" BORDER="2"></p>
Which is outright wrong!.
Apparently, when you have a Windows system and/or a MS browser, something is "repairing" that on the flight.
(I use not only Firefox, but it runs on Linux (openSUSE))