21.—(1) The Ombudsman must not investigate—
(a)any action in respect of which the person aggrieved has or had a right of appeal, complaint, reference or review to or before a tribunal constituted under any statutory provision or by virtue of Her Majesty’s prerogative,
(b)any action in respect of which the person aggrieved has or had a remedy by way of proceedings in a court of law.
(2) But this is subject to—
(a)section 78 of the Northern Ireland Act 1998 (investigations involving discrimination or making oaths or declarations), and
(b)subsection (3).
(3) The Ombudsman may investigate—
(a)notwithstanding that the person aggrieved has or had such a right or remedy as is mentioned in subsection (1), if the Ombudsman is satisfied that in the particular circumstances it is not reasonable to expect the person aggrieved to resort to or have resorted to it, or
(b)notwithstanding that the person aggrieved had exercised such a right as is mentioned in subsection (1)(a), if the person aggrieved complains that the injustice sustained remains unremedied thereby and the Ombudsman is satisfied that there are reasonable grounds for that complaint.