Working: Kingston 4GB CompactFlash Elite Pro 133X
Worked straight away. No need to mess with any commands to get it changed from removable to fixed.
UPDATE:
I can no longer recommend this card. After adding an accelerator to my A1200, I can no longer reliably boot from it. Sometimes at power up, the machine will boot from it fine. Other times it will go to the Insert Disk screen. A simple Ctrl A+A and then it will boot off it. For an unexpanded machine probably fine, add in an accelerator and for what ever reason it has issues.
Also, doesn't work via PCMCIA.