It seems I committed the heinous crime of linking to someone's site's images in a previous posting on here. Apparently this is considered "bandwidth theft" which is a rather odd idea.
The original site had a good item on various types of BT socket and joint boxes, but only a couple of pictures were relevant to illustrate my blog posting. I was careful not to copy the images though.
I have since changed the post so that it has a link to the whole page and not just a couple of smaller images. To me this seems to mean a lot more bandwidth used as people load the whole page and all of the images on following the link, and not just the ones I originally referenced. I have not heard the term "bandwidth theft" before in this context but insisting on a link to the page not just the relevant images seems to counter the suggestion of "bandwidth theft" somehow. The web server in question was happy to serve the images even though it knew that they were referenced from another page (referrer header in request) and so one has to assume that the author was happy about serving such images to my readers. Apparently not.
The logic of the complaint seems to elude me slightly, but as a breach of an arbitrary protocol, I do offer my apologies.