Is it the battery ?

My Mk1 Clipper runs fine all week (even in the snow) then when i come to start it after leaving the car in the garage all weekend it tries to turn the engine over one or twice then the immobiliser light flashes on and i have to disable it with the plastic key and then it does the same again, put the battery charger on the battery and its still fully charged.

Any ideas ?

I have ran volt checks on the battery and it seems fine on tick over - charging and start up etc..

Is there any quick way of disabling the stupid immobiliser ?

Is it the battery or the immobiliser, causing the fault? Have you done proper checks to determine which one it is?

To check battery: fully charge, then wait 12 hours, then check the voltage at regular intervals. 12.70V or thereabouts is 100% charged. 12.4V is 75% charged.

To check immobiliser: with a fully charged battery, connect an ammeter in series with one of the terminals, engage the immobiliser and observe the current draw over a period of time (so it can go into 'sleep' mode too). Check for other devices too and eliminate them by taking out their fuses, eg clock, interior boot light, possibly other interior lights, etc.