The 90 hereditary peers still sitting in the House of Lords may have won a reprieve following the Commons chaos on the issue earlier this week.

Critics say any move to remove the peers, who were elected by their peers, would turn the upper house into an entirely appointed chamber and secure Tony Blair's desired outcome by default.

Lord Lipsey, a Labour peer, announced yesterday that he will introduce a bill next week that would have the effect of ensuring that the hereditaries were eventually removed from the Lords, leaving it all-appointed.

Sources say that the prime minister still "committed" to limited changes to the upper house following this week's developments.