Key symbol on dash?
 

I've wired in a remote start to my bugeye but it will only work when the key is in the ignition??!!! so not much use.

I have worked out its to do with the "key" symbol on the dashlights.

The key only has to be in the ignition for it to work, it doesnt have to be turned.

Is there any way of disabling this symbol or is there an immobiliser in the key?

Yes there is. A small transponder chip in the key that has to be near the ignition to start the car.

but I have seen bugeyes with remote starts so how is it done?

A crude way is to take the chip out, tape it to the inside of the cowling. That will elimante your main immobiliser, which is why you can't get CAT1 alarms with remote start.
I'm sure a pro would just eliminate that immobiliser another way.
Either way is bad in my eyes.