An optical frequency comb, based on a stretched-pulse, mode-locked erbium fibre laser, has been developed to measure the clock transition frequency at 445 THz of a Sr(+) single-ion optical frequency standard. The comb employs separate amplifier branches for the control of the carrier-envelope offset frequency and for the measurement of the clock frequency of the optical standard. Continous locking periods for the comb of over three days have been observed.