No more power for unelected judges rather than elected parliamentarians. No constraint of a future Parliament. No restriction of economic and social rights by their definition at an arbitrary point in time.
So, no written Constitution. And no Bill of Rights.
As for Brown’s Presbyterian conscience, I have no doubt that he is sincere. What I cannot see is that any of this has come as any sort of surprise to him. He has been an MP for 26 years.