asked the Secretary of State for the Home Department what are the criteria for determining whether parliamentary constituency boundaries are to be subject to interim reviews.

There are no statutory criteria. Under section 3(3) of the Parliamentary Constituencies Act 1986 it is for the commissions to decide whether or not to carry out an interim review of the area comprised in any particular constituency or constituencies. I understand that the Parliamentary Boundary Commission for England would normally carry out an interim review in any case where constituency boundaries needed to be aligned with altered local government boundaries, unless a general review or further local government boundary reviews affecting the area were in prospect.