The periodic reviews of parliamentary constituencies in Great Britain require the Parliamentary Boundary Commission in each country to propose any necessary changes in order that constituencies shall be as near the electoral quota (i.e. the average electorate per constituency) as possible, within certain constraints. For each unit (county, London borough etc.) with which they work, the number of potential solutions to their problem is very large. This paper describes a computer program that can be used to inform the Commission about all those solutions, so improving the information base from which they select the new set of constituencies.