It is the largest-ever closure plan by the company and will radically change the face of the bank, according to Unite.
Brown Details Economic Proposals
Gordon Brown will set out a programme for jobs, economic growth and tackling poverty using the new powers of the Scottish Parliament when he addresses business leaders in Glasgow.
The Labour MP will detail specific proposals, including 17 new powers for Holyrood, which he is calling on the Smith Commission to endorse.
The commission is tasked with taking forward further devolution in Scotland following the independence referendum.
Mr Brown will also use the State Of The City Economy Conference to outline Labour's plans to use a tax on banker's bonuses to fund a £200 million scheme to end youth employment in Scotland.
The former prime minister also wants to establish a joint UK and Scotland taskforce on "globalisation and jobs'', and create a new community service organisation Serve Scotland to "empower communities in the fight against poverty''.
He will tell the conference: "Someone, somewhere, with some vision of the future and some sense of what Scots can now agree upon, must demonstrate that we can break free from the deep divisions that are hurting Scotland and show how Scottish people can unite around a bold, radical and innovative programme of social and economic change that respects the result of the referendum - more powers for Scotland within the United Kingdom.
"While the SNP's answer to globalisation, slow growth, poverty and inequality is always 'independence'; the better answer is global co-operation, investment in education and innovation, a strategy for full employment and the empowerment of poor communities through redistribution of resources to them. And these policies are best achieved by a strong Scottish Parliament but not losing the benefits we have by being part of the UK.''
The former PM, who played a key role in helping to secure a No vote in the referendum, will tell the conference that Scotland must "co-operate and co-ordinate economic policies with our neighbours and the rest of the world''.
The SNP claims a "Hard Brexit" will cost 80,000 jobs in Scotland.
A bullet has been recovered from a tree where a man was shot near a primary school.
Scotland's jobless total rose by 11,000 in the three months to November.
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