Parliamentary boundary reviews in the UK are undertaken to remove - as far as is practicable - inter-constituency variations in the number of electors. Their impact has almost invariably favoured the Conservative party - largely because population shifts between reviews tend to favour Labour with the movement of electors away from the inner cities and old industrial areas. That has been the case again with the Fifth Periodical Reviews conducted by the Boundary Commissions for England and Wales. The next general election will thus be slightly easier for the Conservatives to win than if the boundaries used for the 2005 contest were to be retained. But not much easier. Recent elections have seen very substantial biases operating in the translation of votes into seats favouring Labour. The biases are the result of the interaction of several geographies - of constituency size, abstentions and party support- only one of which (size) is directly tackled by the reviews. Unless those other geographies are changed the next two or three UK general elections are likely to see a continuation of these marked biases.