The immobiliser can be overidden by inputting the security code using the driver's door key. You will need to have the original emergency key access code. If you don't have it this should be available from a Rover dealer if you give them details such as the VIN no.
To input the code..hang on I'll get my handbook... right, here we go (these are the instructions for an R25 but I recall using the same method on my 1993 R414)
1) Using the key turn the driver's door lock (clockwise) to the lock position and hold in this position for at least 5 seconds. Then return the key to the centre position.
It is now possible to enter the four digits of the security code as follows:
2) Enter the first digit of the code.
If the first digit is 4, turn the key to the UNLOCK position 4 times. Ensure the key is FULLY returned to the centre position after each turn of the key.
3) Enter the second digit of the code
If the second digit is 3, turn the key to the LOCK position 3 times.
4) Enter the third digit of the code by turning the key the appropriate number of times to the UNLOCK position
5) Enter the fourth digit of the code by turning the key the appropriate number of times to the LOCK position
6) Finally turn the key to the UNLOCK position one more time; this will re-mobilise the engine.
If the code has been entered correctly the alarm will stop flashing and the engine can be started.
Hope this helps
mark, December 2009