Rover owners: Rover 25 stuck in gear?

Hi guys, just had my gearbox out to change the clutch, and have lifted the gearbox back into the car and it's all secure in place. Yesterday I had my friend reconnect the gear linkages to the gearbox and when he was doing it the shifter rod moved in and out freely, changing gear. Nothing has been touched in that area since, but I have now tried to move the gear stick with the linkages connected and it is stuck. I disconnected the linkage to find that the shifter rod would not move, I think it is stuck as far in as it goes. Any ideas why it's stuck or how I can fix it?

Any help at all is greatly appreciated.