Leakage characteristics, influenced by radial growth are determined computationally for a six-tooth straight-through rotating labyrinth seal of a Gas Turbine (GT) secondary air system. The computational methodology is validated against the available data in the literature. The influence of seal location and its radial growth on the leakage performance is examined for a wide ranging speed, temperature and pressure ratios. A comparison of the structural deformations due to centrifugal and thermal effects showed that rotation has negligible effect for a smaller rotor (R25 configuration). A considerable reduction in leakage flow rate is noticed for large rotor (R75 configuration) due to both centrifugal and thermal effects.