Wordpress Site - Fix Speed/Load issue

Hi there, around 3 weeks ago our website has become extremely slow. It was fine before and other sites on the hosting account are running fine. The site is www dot laptopbag dot org dot uk We need this speed issue fixed, it takes a long time to open any page on the website. We have deactivated all plugins etc on the site and still no difference, we are unsure of what the issue is.