Clinical evidence indicates that a third of patients with epilepsy are refractory to anti-epileptic drug treatment. For some of these patients better seizure control can be achieved by surgical treatment in which the seizure focus is localised and resected while avoiding injury to crucial cortical tissues. In this paper, non-seizure (interictal) epoch of electrographic recording was used to calculate the functional synchrony between different cortical regions. This synchrony measure was then used as the connectivity parameter in a computational model of transitions to a seizure like state. The seizure focus was localised using this model and the surgical intervention procedure was simulated. It was shown that the in silico removal of a subset of seizure focus can decrease the likelihood of a seizure in the model. The in silico results were also compared with the clinical outcomes and a convincing agreement was shown for five out of six patients; sixth being a counter-example. These methods may aid in the identification of the seizure onset zone using the interictal electrographic data. Moreover, it may facilitate neurosurgeons to investigate alternative cortical tissues to operate on if the seizure focus cannot be operated.