I have a website: <snip> that used to rank very well in Google for keywords such as "formal letters", "personal letters", "letter writing" etc. Once the penguin update came out on the 24th April 2012 the website dramatically dropped in ranking. The website ranked very highly, nearly always in the top ten for many of the keywords previously, but after the Penguin update website it did not rank well at all and for some keywords dropped off the listings all together.
I have attempted to dilute the anchor text of links coming through to the website in case this was the reason but there has been no effect on rankings. Even for our brand the "good letter writing" keyword which we were previously at number 1 for has been effected and we currently rank 12.
Webmaster tools is setup and we have not received any messages about spam, I just can't for the life of me work out why our website no longer ranks, can someone please help?
Thanks in advance,