Ms Dugdale will talk for the first time about her voluntary work as an advocate for people with mental health and addiction problems and how it has influenced her values.
The day after she unveiled her shadow cabinet, she will also draw on her experience of being outpaced by high-achieving, privately educated students when she studied law at Aberdeen University to rail against “the injustices working class people face”.
“For years now I have volunteered as an advocate for vulnerable people with complex needs in Edinburgh – people battling against addiction, people with mental health problems, young people living rough, in and out of prison,” she will say.
“We work together to get the support they need from the NHS, from government, to help them get back on their feet and towards living independent lives. Sometimes we succeed, too often we don’t.
“I will never talk about the troubled, brave individuals I have worked with but the experience of standing beside them has taught me so much. That those who could have so easily been written off have hopes and dreams like the rest of us.
“That government, when it responds to what people need, working with, not just for, them, can transform lives beyond recognition, and that when government fails it can have a devastating impact on vulnerable lives.”
On her own experience of life, she will talk of the contrast she saw between privately educated students and those from less well-off backgrounds when she read law at Aberdeen.
“I first felt the unfairness of inequality when I moved from primary school in leafy Elgin to secondary school in urban Dundee. Expansive sports fields replaced by playground concrete. An average pupil in prosperous Elgin, I was suddenly near top of the class in my new secondary in Dundee.
“When I went to study law at Aberdeen University I found the wheel had turned again and I was surrounded by privately educated pupils whose backgrounds I couldn’t relate to and whose achievements I couldn’t compete with.”
Yesterday the Labour leader and her colleague Jenny Marra went to the Punjabi Junction Cafe in Leith to announce the party’s new front bench team. The new deputy leader Alex Rowley will have responsibility for strategy and policy.
Ms Dugdale said her front bench would be charged with communicating Labour values rather than shadowing SNP ministers so their portfolios do not necessarily match opposite numbers in government.
The job of holding the government to account will fall to Jackie Baillie, who has been appointed public services and wealth creation spokeswoman.
The remainder of the 12-strong team will be: Ms Marra as equality spokeswoman; Iain Gray, opportunity spokesman covering education; Graeme Pearson on justice; Ken Macintosh on communities; Sarah Boyack on environmental justice; Clare Baker on democracy (covering the constitution); Mary Fee on reform (covering party and parliamentary reform); James Kelly as business manager and Neil Bibby as chief whip.
Left-winger Neil Findlay, leading Jeremy Corbyn’s campaign north of the Border, was a notable omission.