How would PR have changed the face of Parliament?: The Supplementary Vote System

How it works: Supplementary Vote is a simpler version of Alternative Vote: voters mark only their first and second preference. If a candidate gets over 50 per cent of the first preference he or she is immediately elected. Otherwise, all but the two top candidates are eliminated and their second preferences are allocated.

Second preferences of the eliminated candidates do not count.

It is in essence the French system, except that you vote twice on the same day, instead of a week apart.

For: The simplest system. Constituencies remain the same, and each constituency has only one MP. The traditional 'X' is retained as a voting method. Campbell-Savours says it is preferable to AV, because 'You're voting for who you love, not who you can put up with'.

It is 'an engine for tactical voting', and the limited choice prevents fragmentation of the opposition vote.

Against: 'It is only five per cent of the way down the road to proportionality.' says Professor Philip Norton of Hull University. Others ask: Is it worth convulsing the system for so little real change?

Dale Campbell-Savours' figures (in table, below) are worked out on 1992 general election figures on the assumptions that, (a) That the Liberal Democrat secondary vote is split 50-50 between Tory and Labour; (b) 90 per cent of the Conservative and Labour secondary vote goes to the Liberal Democrat candidate.

However, the LSE figures for Alternative Vote show that only about 50 per cent of the secondary Labour or Conservative vote goes to the Liberal Democrat - giving the Liberal Democrats a minimum of 30 seats.)

----------------------------------------------------------------------- How it would have changed the Commons ----------------------------------------------------------------------- Con Lab Lib Dem SNP/PC Green MPs 304 (46.7%) 271 (41.5%) 46-49 (7.1-7.5%) n/a n/a -----------------------------------------------------------------------