PlusNet's server inserting blank lines on webpage - help me.

[#1]

Hi all. I hope someone can offer an explanation (and possible solution) as to why blank lines are inserted on my webpage under one particular image. The same coding is used for multiple images of the same size on the same and other pages, which work fine, but this one particular image is proving a problem. The page displays correctly on another, non-PlusNet server. If I remove the image, there is no problem, if I halve the image size, I halve the problem. I could work around it but it would cause inconsistency.
Maybe PlusNet's server is being awkward because it thinks I'm displaying an image of local competition - the image being captioned 'Sheffield industries' (from the game, Chris Sawyer's Locomotion). The only solution I can come up with is just to remove the image  :'(.
A direct link to the page is: http://www.educat.plus.com/lpages/chal-scen-prog/gbi1955.htm
The first image on the page is the problem, the second, further down uses the same coding and displays correctly.
A direct link to the half-size image test page is: http://www.educat.plus.com/lpages/chal-scen-prog/2-gbi1955.htm
The coding is:

<p align="center"><img src="gbi1955-img/Sheffield industries.jpg" width="560" height="420" 
border="0" alt="Sheffield industries"><br>
<span class="caption">Sheffield industries</span></p>

I hope someone can help with this - or give the server a good kick.

[#2]

The blank lines are in the image itself, not in your web page.
Having downloaded the image and viewed it in my image editor, it looks like the image is incomplete... The blank section is actually corrupted so cannot be shown thus giving a blank section.

[#3]

Ah thanks, Peter. It must have got cut off during the upload. I didn't get any error messages so this is the last thing I would have thought of.
Ee, there was me fiddling around with the page.   Thanks again, I'll re-upload the image.