First Minister Nicola Sturgeon will attend the opening ceremony of an historic General Assembly of the Church of Scotland which will see the Archbishop of Canterbury join a Kirk debate for the first time.

Senior judge Lord Hope of Craighead, this year’s Lord High Commissioner – the Queen’s representative at the General Assembly – will read out a letter from the monarch to the assembly which more than 850 commissioners from across Scotland, the rest of the UK, Africa, Asia, North America, Europe, the Middle East and the Caribbean have registered to attend.

The Archbishop of Canterbury is to make history when he becomes the first head of the Church of England to take part in a debate at the General Assembly.

The Most Reverend Justin Welby will speak about a landmark report, which proposes that the two denominations enter into an historic ecumenical partnership, on Wednesday.

The Lord High Commissioner also inspected the guard of honour from the Royal Highland Fusiliers, 2nd Battalion the Royal Regiment of Scotland, as he took up residency at the Palace of Holyroodhouse for the week-long gathering.

The General Assembly which starts on Saturday in Edinburgh has the power to make Kirk laws and set the agenda for the coming months or even years for the administrative councils, committees and departments of the organisation.

Last year the General Assembly took the historic step of recognising ministers and deacons in same sex civil partnerships following years of debate.

On Saturday commissioners will be asked to vote on amending church law to recognise ministers and deacons in same sex marriages as defined by the Marriage and Civil Partnership (Scotland) Act 2014.

The Kirk said that, if successful, it would not imply the Church will permit its ministers to solemnise same sex marriages.

The Church said it maintains its traditional view of marriage between a man and woman, but the change would extend individual congregations ability to "opt out" if they wished to appoint a Minister or a Deacon in a same sex marriage as well as civil partnership.

Other topics to be discussed include the European Union referendum, corporal punishment of children, climate change, the refugee crisis and exploring ways of growing the Church via the Internet and social media.

The Right Rev Dr Morrison stands down from his 12-month role as Moderator, the Kirk’s ambassador at home and abroad, and will be replaced by the Rev Dr Russell Barr, the founder of an Edinburgh-based homelessness charity called Fresh Start.

The Right Rev Dr Morrison said: “It is with a sense of relief and gratitude to the General Assembly that, on, I pass on the moderatorial baton to Dr Barr."

The 62-year old Mr Barr, who is minister at Cramond Kirk, Edinburgh, said he was "excited, honoured and overwhelmed" and added he will continue to highlight the plight of homelessness in Scotland.

"I will seek to use the role to raise moral and ethical issues and publicise the important part the Church plays in public life."