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Jeremy Corbyn is preparing for his first annual conference as Labour leader, which will include a vote on the party's nuclear policy for the first time in over a decade.

This debate, as well as recent differences of opinion between the leader and his shadow cabinet, have focused attention on the complex process by which policies will end up in Labour's manifesto.

Here's a guide:

Annual reports

Labour Party policy is the result of consultation with members, elected representatives (MPs, MEPs and councillors) and the trade unions.

The main body for shaping policy is the National Policy Forum, an elected group of over 200 people representing councillors, trade unions, socialist societies and MPs. It produces reports on the different policy areas, which are presented at annual conference and either accepted or rejected in a vote.

Image caption Tony Blair set up the National Policy Forum

For manifesto policy, there is a formal consultation process which culminates in a meeting of the forum the year before the general election to agree the final details of what will form the foundation of Labour's next manifesto.

This document is then put before conference for adoption as Labour's policy programme. No proposal is included in the party programme unless it is adopted by a majority of not less than two-thirds of a conference vote.

Manifesto pledges

Importantly, conference votes whether to accept or reject large policy documents as a whole - not on individual policies or line by line.

When Labour is not in government, the final say on which items make it into the manifesto is made at a meeting of Labour's ruling National Executive Committee (NEC), the shadow cabinet and key figures from both the Parliamentary Labour Party and the National Policy Forum.

Image copyright PA

Image copyright Reuters Image caption Labour's policy has to adapt to the daily House of Commons schedule

Day to day policy-making on Labour's position on votes that arise in the House of Commons is slightly different. It relies on a looser and more informal process based on consultation and consent with the shadow cabinet, Labour MPs and the NEC.

Setting the agenda

The annual autumn conference is described by Labour as "the ultimate authority in the party".

Labour's Conference Arrangements Committee oversees the agenda and sets the timetable. If it accepts a motion, they are grouped into topics and conference delegates choose four topics submitted by local Labour parties and four topics from trade unions.

Image copyright Getty Images Image caption Barbara Castle, Harold Wilson and Tony Benn sing Auld Lang Syne at the end of Labour's 1979 conference

Once the broad topic headings have been picked, all the representatives of the local Labour parties or trade unions who tabled a motion on each topic must get together and put all their different motions into one "composite" motion that is acceptable to everyone.

The final composite motions are then scheduled for debate on the conference floor.

Who gets to vote?

Roughly 10,000 people are expected to attend this year's Labour Party conference but only around 1,000 of these are delegates eligible to vote.

Delegates come from three places: local Labour parties, trade unions and socialist societies.

Image copyright AFP/Getty Image caption People who have joined Labour since Jeremy Corbyn became leader will not be eligible to vote at conference as delegates

Crucially, these delegates will not include any of the 62,000 new members who have joined Labour since Jeremy Corbyn became leader. That's because to be a delegate you must have had 12 months' continuous party membership at the delegate registration deadline, which was in June this year.

How does conference voting work?

The local parties and trade unions (along with other affiliated socialist societies) each make up 50% of the vote on the conference floor.

Delegates can vote for something to be included in the party programme based on a majority of not less than two-thirds.

Image caption Trade unions can submit motions to be discussed at conference

But remember, only eight topics are chosen for debate at conference. Since, as explained above, all groups who submitted motions on a certain policy area have to get together to agree a final draft motion acceptable to everyone, what's adopted often ends up being quite vague and agreeable to everyone.

How much power do unions have?

Affiliated trade union members get half of the votes at conference, but this is on a one member, one vote basis. Former Labour leader John Smith abolished the trade union bloc vote and replaced it with individual votes for each union delegate.

Image copyright PA Image caption Former Labour leader John Smith, seen addressing the 1989 conference, changed the way unions voted

This meant union bosses could no longer wield huge numbers of votes which would sway party policy. Unions have also drastically reduced in size from the days when they would dominate Labour policy-making.

Can the leader impose policy on their shadow cabinet?

Any leader has scope to influence policy through personal authority.

Jeremy Corbyn, for example, can refer to his decisive mandate of being elected by almost 60% of voters in the Labour leadership election. But that doesn't mean he can dictate policy.

Members of the shadow cabinet and Labour MPs are well represented on Labour's key policy-making bodies.

Image copyright PA Image caption Not all of Jeremy Corbyn's shadow cabinet share his views on policy areas like defence

The threat of shadow cabinet resignations is a serious consideration for any leader. Lord Falconer has already publicly threatened to quit as shadow justice secretary if the Labour leader campaigns for the UK to leave the European Union.

And Labour MPs could simply choose to rebel against official party policy in any Commons votes on issues they are at odds with Jeremy Corbyn on, with likely clashes set to include military intervention in Syria and Trident renewal.

Some Labour MPs argue they were elected in their constituencies on their own mandates according to the policies outlined in Labour's 2015 general election manifesto.

Could Jeremy Corbyn end up in a position where he's forced to promote a party position that he personally disagrees with?

Yes. Policy is made collectively in the Labour party, not by any single individual.

Politically all Labour leaders have no doubt been constrained at times by the overwhelming view of the shadow cabinet, or threats by the trade unions to cut off their funding.

Image copyright PA Image caption Labour's conference will debate the future of Trident

Both those who support and oppose Jeremy Corbyn seem agreed on this point.

However, the leader's office exerts a significant degree of influence, and is on occasion able to bend the ear of the party's policy-making institutions and representatives.

Will Jeremy Corbyn change Labour's policy making process?

During the Labour leadership contest Mr Corbyn repeatedly said he wanted to "democratise" Labour's policy-making process and "empower party members".

As leader he has suggested decisions taken at party conference will become binding policy. Asked whether scrapping the Trident nuclear weapons system would become party policy if conference votes that way, he told The New Statesman: "Well, it would be, of course, because it would have been passed at conference."

However, the Labour Party's rule book appears to stipulate that if Mr Corbyn does want to change the process (as Ed Miliband and other opposition leaders have tended to do), he must first ask the National Executive Committee to put any such changes on the conference agenda. These must then by passed by delegates in a vote at conference.