Companies Act 1985

193 Perpetual debentures.E+W+S

A condition contained in debentures, or in a deed for securing debentures, is not invalid by reason only that the debentures are thereby made irredeemable or redeemable only on the happening of a contingency (however remote), or on the expiration of a period (however long), any rule of equity to the contrary notwithstanding.

This applies to debentures whenever issued, and to deeds whenever executed.