Improve Rankings!

Hi, I run a painting and decorating firm in London and have been doing great SEO work on our website for the past 8 years. We rank on first pages for most of the keywords we aimed for but our rankings are slowly starting to decline in position. We require advice once you have had a look at the website to inspect the current errors that are causing this decline and tell us what services you can offer to improve the rankings again, where are we going wrong? We are happy to employ you to work on the SEO of our site once you are ready! www.painters-decorators-london.co.uk Thanks!