Retro,
Just checked out the Sunbury Health Centre in the article and they need to have more GPs. They have 12 serving 1,600 patients each = 19,200. However that assumes they all work all of the time. When you consider holidays and sickness, they probably need at least two more GPs.
Apparently, since the GPs negociated new contracts in 2004, the number of GOs setting up their own Practice has plummeted. They are earning such good wages salaried, that there is no incentive to go it alone.