Srarts, but stops..

I managed to sus out the new loom, so alls well on that front.
Wired up the solenoid etc too, so I could start the beasty.
It fired up, but as soon as the ignition key was released to position 2, it died.
Tried again, started but died when released, I started flicking between 2 and 3 when it fired, and it would rev it, on off, on off etc, using pos 3 as a throttle.
So, what I imagine its doing is shutting electric off to the engine when it goes to pos 2 on ignition, instead of it firing.
Is the coil + feed being cut off?
Hoping someone can help please?
series 3, 1971, 2 1/4 petrol

assuming four terminal ignition switch position 3 should feed starter solenoid (red/white ) position two should feed (white) ignition coil oil pressure,choke and alternator charge lamps

I have them in the correct positions on ignition- solenoid, but the only thing is I dont have is the alternator/oil pressure connected up to main harness or solenoid, I left it off because I was trying to prove the engine.
Does it need to be connected to run engine? I thought it just charged the battery, but there is probably more to it than that ..

no the alt/oil not needed to try out but you should have a feed on the ignition coil when ignition switch turned to position 2 and when in position position 3 cranking starter solenoid

Sounds like the coil is loosing its + supply.
Is the ignition switch for a petrol or a diesel?, it sounds much like you have a diesel ignition switch and the coil is connected to what would normally be the heater relay output on the switch.
Put a test lamp accross the coil and switch the ignition to 2, if the lamp does not light untill the switch is in pos 3 then summats up, could be a knacked switch.
You can make a test lamp from an old bulb holder and bulb, usefull gizmo.
Edit: summat else just occured to me, some landys have a ballast resistor for the coil, this is to aid starting esp when its cold, if there is a white ceramic do dah around the coil about the size of a small screw driver handle check the connections, and measure the resistance with a multimeter, should be around 5 to 10 ohms.

Hi, its funny you should ask if its a diesel or petrol...
it started life as a petrol, but was converted to a diesel (badly)
there is evidence on the back of the ignition switch that it has been tampered with, its held together with cable ties.
I was wondering if the original petrol ignition has been opened up, and bodged to suit a diesel... if this was the case, i should see straight away if i opened it, maybe terminals being linked or something.

If the switch has been messed with and is held together with tie wraps then I'd be suspicious of it bigtime, thats probably your fault.
Instead of relying on a messed up ignition switch maybe you could get an scrapper and replace it, even if its not the actual problem.