Tiptree United are on the verge of clinching the title while Ely City have just about secured runners-up, meaning there is still one place up for grabs.
Against O'Sullivan, the 28-year-old from Tiptree was undone by a failure to make the most of a number of opportunities that came his way as his opponent struggled to hit top gear.
There aren't many places in Britain where a single employer has played such a big part in the area's history and needless to say, many companies are not doing as well as Tiptree, at home or abroad.