I had the same issue recently, 
Check the back of the ignition switch to see if you have power at the constant ignition circuit, if yes check power at the fuse box ( both sides of the fuse ).
Theres two circuits for the the ignition, a 12v starter circuit so when you hit the stater position on the key the coil gets a hit of straight 12v to give a better spark for an easier start. The 2nd circuit runs through a resistance wire to supply around 9v to the coil for constant running, this lower one i believe is used so your points last a lot longer.
I had issues finding the resistance wire so i ended up rewiring the circuit through a ballast resister and disconnected the original wire.
To test this throw a multi meter on the positive coil side whilst cranking which should show 12 volts, when release the cranking back to ignition you should still see around 9 volts.

Still troubleshooting, today checked the dizzy firing order and timing and all looks ok.
 
I did notice that the pink resistance wire heats up considerably under accessorie and cranking, any idea's why this could be happening? I will try and get some photos up in the next few days.

Thanks Mickos.
 
Here are a few photos of the resistance wire and coil:



This is the resistance wire connection point.
 
 

So by by-passing you mean disconnect the current resistance wire and replace with standard wire? Before i go and run an new cable, on the coil (-) i have black cable from dizzy connected and on (+) i have a red/green wire then connected to that i have two pink cables connected together as the photos i have posted in my last post, is this correct?

Thanks, will give it a shot. I bought the car in 100 pieces so has never worked under my ownership :)