Without first hand experience, no one could say for sure.
Just make sure the car is nice and warm before it does the emissions testing. If the remaining cat is nice and warm you would probably be fine.
Almost like my old Astra VXR - that had 2 cats, the main one and a "precat" straight after the turbo that got the car to it's proper emissions levels quicker. You could happily dispense with the precat as the main cat was plenty to sort out the emissions and it always passed MOT tests.