Ann Widdecombe undergoes odd makeover …
Ever done a search for Ann Widdecombe? Me neither until today. There's an interesting image shown, as you can see - and from an SEO point of view, it's as interesting as it's funny.
Ann Widdecombe has a new hairdo
The image Google is showing as the number one result is from the www.greatwigs.co.uk website. However, the image in question is no longer on that site, although it is linked to from this Guardian article (where it says "Ann, as ever resembling a peroxide Friar Tuck").
Try to click through to it, and you get a 404 page not found. So why on earth is Google returning a non existent image as the first result? And is that all you need to rank first - one link from the Guardian? Or does its incongruity mean that so many people click on it that Google has been fooled into thinking it must be relevant?
Unfathomable, then again image results tend to be rather more difficult to make much sense of - have virtually given up trying to optimise for them
There is a description underneath the main image which says 'Friar Tuck gets nicked for Robin ... a still from Ann Widdecombe Versus (ITV1)'. The image just before it in the markup has an alt of Ann Widdecombe and so I guess that G has deemed that because these have been referenced together on such an authority site, big G deems that Ann Widdecombe and Friar Tuck are related and relevant. The span has a class of 'caption' too which could add weight.
You can see how much 'relevance' value this strap line text passes here. If you search for 'Ann Widdecombe Photograph', you get this picture of her with some lovely goats.
http://images.google.co.uk/images?um=1&hl=en&tbs=isch%3A1&sa=1&q=ann+widdecombe+photograph&btnG=Search&aq=f&oq=&start=0
The image doesn't have photograph in the filename, neither does the alt. The only reference to Photograph on the page is in the text appearing withing the 'caption' class beneath the image. It seems the Guardian + the caption text does have some serious clout.....or perhaps it's just the goats
One of google's finest results! I'd like to think that widdecombe probably googles herself daily and is faced with that image
- will there be a rant from her in whatever crappy newspaper gives her a column complaining about how Google is broken and she's going to be suing for defamation? Trust me widdecombe, that is the most flattering pic of you you'll ever see 
Interesting case because it gives an insight into google image ranking factors. Some great insights from David above. The only think I would add (apart from this theory) is that a direct link to an image file is probably a very strong signal to Google - after all who links to an image rather than embeding it?