Which preposition to use with irremovability

of Occurrences 2%

They next set before me, as a terrible warning, my uncle, another brother of my father's, who had gone to the Bar, and I will not say never had any practice, for I believe he practised a good deal on the Norfolk Broads, and once had a brief at sessions concerning the irremovability of a pauper, which he conducted much to the satisfaction of the pauper, although I believe the solicitor never gave him another brief.

Which preposition to use with  irremovability