Since the then prime minister outlined justifications for her views on capitalism and social reform, the Kirk has been immersed in political issues. Two decades ago it was an outspoken critic of the Tories, the poll tax and Trident.

This year the Assembly, which opened yesterday, will turn itself to Iran, the death penalty, gambling and affordable housing.

In the coming days the Kirk's influential Church and Society Council will take the UK government to task over its attitude towards Iran's efforts to develop nuclear weapons. It will accuse ministers of "gross hypocrisy" in trying to prevent Iran from arming itself while replacing Britain's Trident weapons.

The Kirk will also revisit the issue of capital punishment. Though the death penalty was abolished in Britain in 1969, the Kirk has never taken a definite stance on the practice.

However, in the wake of the controversial execution of Saddam Hussein last year, the Church and Society Council has re-examined the international situation and concluded that the "death penalty brutalises the society which practises it".

It will ask the Assembly to accept that "capital punishment is always wholly unacceptable and does not provide an answer even to the most heinous of crimes".

This week the church will also address internal issues such as the tenure of ministers, which could see it ending a tradition stretching back to the beginning of the 19th century.

Ministers have the right, once appointed to a parish, to remain there until retirement if they so wish. It is extremely difficult to remove a minister unless he or she is found guilty of a serious misdemeanour.

A new report is seeking to change this, putting forward a set of proposals that will place the relationship between ministers and their congregations on a new, less permanent footing.

These vary from the creation of a "reviewable" or "adjustable" tenure to bigger shifts involving the creation of employment contracts, which would bring ministers under the civil law system for the first time.

The backdrop to such debates however, is one of falling membership of the Kirk, which dropped to a new low in the past year, dropping below 500,000.

Contributions from congregations, meanwhile, have risen 2.1 per cent. The issue of giving was raised during the opening session yesterday, when the Council of Assembly announced there would be a rise in the sums required from congregations.

Helen McLeod, convener of the council, said: "Last year the amount to be contributed by congregations was reduced by £1 million following a freeze the year before. This year we are proposing a slight increase of £400,000 or just under 1 per cent. This means that the amount to be contributed by congregations for 2009 is still less than it was in 2006."

Mrs McLeod added that it meant that local churches would retain almost 82 per cent of the anticipated increase in parish incomes.

But the issue of money raised by individual churches and how much they can hold on to is likely to be a point of heated debate.