Crucial meetings of the Ulster Unionist Council have become a regular feature of the peace process as party leader and Northern Ireland First Minister David Trimble returns again and again to seek his divided party's backing for the Good Friday Agreement.

This Saturday's meeting is the sixth occasion where Mr Trimble has faced a potentially tight corner, though the council has met on many other occasions since 1998.

Each vote has been fiercely fought by the pro and anti-Agreement blocks, with Mr Trimble narrowly winning on each occasion.

This Saturday will be no different for Mr Trimble - every vote is likely to count.

The council

The policy-setting council is drawn from all shades of the party. But the significant amount of power it wields over its leaders sets it apart from the composition of other modern political parties.

The council's exact composition is difficult to pin down as there are small changes happening all the time. But the key groups are roughly as follows:

• Constituency delegates: 680
• Orange Order members: 88 plus
• Elected politicians: 90

Good relationship

The council is renowned for being a highly conservative body, reflecting the continuing importance of the rural unionist vote.

While David Trimble's influence within the council has wavered since 1998, he has succeeded time and time again in maintaining its support for the peace process, if only by ratcheting up that support by a tiny notch at a time.

In April 1998, a week after the signing of the Good Friday Agreement, 72% of the delegates voted in favour of it.

But at least 30% of the council's members have consistently opposed the agreement - and at the time of that vote, many predicted that Mr Trimble would gradually lose support if there was no movement on paramilitary arms decommissioning - it is a prediction that has come true.

That ebbing of support became apparent when Mr Trimble went back to the council on 27 November 1999 to sell it the outcome of the George Mitchell Review.

The scene outside Belfast's Waterfront Hall was dominated by noisy pro and anti-agreement demonstrations with delegates from both sides heckling and being heckled.

Inside, Mr Trimble won the day - but with only 58% of the delegates' support.

In March 2000, Mr Trimble survived a leadership challenge - with 57% of the vote - though his critics would say not convincingly.

Two months later, he returned to the council for a vote on restoring the power-sharing bodies. He won that by 53.2% - and an autumn vote rejecting another pull-out by a little bit more.