Letter: How to share power

Sir: Your account of the d'Hondt procedure used to allocate ministerial portfolios on the Northern Ireland Executive includes several inaccuracies ("Sharing of seats devised in 18th century", 30 November).

Viktor d'Hondt was indeed a Belgian, but could not have been "an 18th- century Belgian political scientist", because Belgium did not exist before 1830. He was a 19th-century lawyer who independently developed his system of proportional representation, which had been pioneered by the American Thomas Jefferson.

The d'Hondt procedure, using the divisors 1, 2, 3, 4 ... n, may be seen as a series of rounds. In each round, one portfolio is allocated to the highest-scoring party. In the first round each party's score is the number of seats it holds in the elected assembly. After the first portfolio is allocated to the winning party, that party's score in the next round is divided by two; the other parties' scores are unaltered, and the party now having the highest score wins a portfolio. When any party wins its second portfolio, its score for the next round is its original seat total divided by three, and so on. The process continues until all portfolios, 10 in the case of Northern Ireland, have been allocated.

Mysterious and unelaborated references were also made in The Independent's article to "the first-preference votes" coming into play. They did so in the allocation of the eighth ministerial portfolio. In this round the Ulster Unionist Party had a score of 9 (27 seats divided by 3), and so did Sinn Fein (18 seats divided by 2). As a tie-breaker the rule used is that the portfolio goes to the party with the highest number of first- preference votes gained in the assembly election - in this case the tie- breaker worked in favour of the UUP.

BRENDAN O'LEARY

Professor of Political Science

London School of Economics

London WC2