Balancing constituency government with proportional representation

A personal proposal retains a roughly 600-seat House of Commons elected by first past the post while creating a 400-seat second chamber allocated by each party's national vote share. Instead of allowing parties to appoint a list, the proportional seats would go to their strongest unsuccessful constituency candidates. Limits on repeated candidacy and consecutive terms would prevent the second chamber from becoming a permanent refuge for habitual losers. The arrangement aims to preserve the tendency toward stable government in the Commons while making votes cast for locally unsuccessful parties count nationally. This is a suggested institutional model rather than a description of the United Kingdom's present constitutional system.