connecting immobiliser on toad a101cl

The alarm is a Toad A101CL, my car is an Austin Mini. I was going to make an immobiliser circuit with the wire that goes from the starter relay to the starter solenoid.(The thickish brown one with the red stipe i think.)

I assume i would need to use a relay. I was going to connect the immobiliser wires to two of the relay terminals and the other two relay terminals between the thick brown wire. Or should it be connected the other way around? Or could i get away with not using a relay?What does everyone reckon?I was going to connect it something like this:-

I am not familiar with the Toad brand alarms, however a starter kill circuit like you describe requires only a negative when armed output from the alarm. This wire would go to either pin 85 or 86 of the relay the other pin would go to the key side of the starter wire or ignition. The cut starter wire would then go to pins 87a and 30 of the relay. That relay you show there does not look like the correct setup it appears that the relay shown only has pins 30 and 87. Installer, IT support, and FFL. I need less hobbies.