Personally I find Google is providing results which are less and less useful, with their recent emphasis on monetising search, indifference to fairness, and lack of transparency as to their ranking methods - it certainly seems as if in this case a draconian penalty has been applied, and there is no effective way to appeal or even find out what the judgement against them was (webmasters very often is not helpful). A penalty of a few places would be completely understandable if they don't like this site for whatever reason, a penalty of 8 pages while other spammy results dominate search terms is not.
I've switched to DuckDuckGo for now and it's pretty good. Compare the results for Tipex (a popular brand of correction fluid in Europe) for example:
https://duckduckgo.com/?q=tipex https://www.google.co.uk/search?q=tipex
https://duckduckgo.com/?q=tipp-ex
https://www.google.co.uk/search?q=tipp-ex&oq=tipp-ex&gs_l=se...
http://www.bing.com/search?q=tipp-ex&go=&qs=n&form=QBLH&filt...
http://www.yandex.com/yandsearch?text=tipp-ex&lr=87
http://www.dogpile.com/search/web?fcoid=417&fcop=topnav&fpid...
http://uk.search.yahoo.com/search;_ylt=An3Le.5YQeHZ499qBVnAQ...