A transmission system for a hybrid vehicle includes a primary input shaft for receiving drive from a primary vehicle drive motor, such as an internal combustion engine. A secondary input shaft receives drive from a secondary vehicle drive motor, such as an electric motor. An output shaft of the system is connected to drive a final drive unit. A multi-speed gearbox is provided to connect the primary input shaft to the output shaft at one of a plurality of gear ratios. An input selection mechanism, in a first mode, connects the secondary input shaft to drive the output shaft and, in a second mode, connects the secondary input shaft to drive the primary input shaft. A clutch may be provided that can selectively connect or disconnect drive between the primary drive motor and the gearbox.