I have been helping a client with this website and his on site SEO too, and his most important keyword is 'Antique Clocks' although for other keywords and keyword sets he doing much better, such as 'Antique Clocks For Sale', 'Antique Clocks London' and so on.
So to get back to what I have done.
I have used Google Webmaster Tools and have the green number score for speed, leverage browser caching, gzip, image compression and so on.
The page loads very quickly, there next to zero errors in W3C validator, we have addressed a lot of his bad links, and have been busy building links and have CDN on the server and had made sure we got good titles, no duplicates and have alt tags and titles on images and links, and there probably more but cant remember.
So I wondered if someone wouldn't mind having a look at this site and seeing if there anything standing out that I may have missed. This will also help in my learning, but please understand that I have had a go at this, but don't get why after 6 months the home page hasn't really moved from page 5 for the keyword 'Antique clocks'