From child labour contracts and industrial machinery to the unusual homes of working families carved into the rock, this episode uncovers the hidden lives of ordinary working people – and follows the teams making sure their stories are never forgotten.

In a quiet Cheshire valley beside the River Bollin stands Quarry Bank Mill. Built in 1784 by Samuel Greg, the mill became a powerhouse of the Industrial Revolution during which new machinery transformed cotton production and helped change Britain forever.

At the heart of the mill is one of last working examples of one the most important of these machines: The Spinning Mule. The Spinning Mule could turn raw cotton into yarn faster than ever before, helping make cotton clothing affordable far beyond the wealthy elite. But keeping this giant machine alive is a full-time job, and every year the Mule must be completely dismantled, cleaned and rebuilt. Technical demonstrator Rex and the team must strip the Mule into hundreds of pieces and service every part before getting the machine spinning again.

As well as the machines, the other crucial part of the mill's productivity were the people. Now a rare new object has arrived at the mill that tells the story of just one worker – an apprentice indenture from 1785 belonging to thirteen-year-old Thomas Payne.

The fragile contract signed him into years of labour at Quarry Bank, part of a system that brought orphaned and vulnerable children into the mills as cheap workers. It is one of the few surviving records of an individual child apprentice. But the document is badly torn and close to falling apart. Conservator Sharon must carefully clean the fragile paper, repair major tears and stabilise it for display. For the team, preserving this single piece of paper means giving one forgotten child a place in history.

Meanwhile, in Staffordshire, another working-class story is being protected at Kinver Edge. Here, a row of remarkable houses carved directly into the sandstone hillside once sheltered generations of local families. The last residents of these real-life hobbit homes moved out in 1960s after which the houses fell into serious decline.

Since 1989, the National Trust has been carefully restoring the cottages to how they once were, from making them water tight to sourcing replica furniture, fixtures and fittings. Now the final house to be restored, Martindales – once home to local postman Harry Martindale – is nearly complete, but one vital feature has been missing: a kitchen range, the true heart of the home.

Today, finally, the missing piece of the jigsaw has arrived - a salvaged historic range that has recently been donated by a member of the public. However, it still needs to be fitted - no easy task when nothing about the rock houses is regular and the walls and floors are carved from the bare rock.

It's not just the houses that the National Trust care for at Kinver. Outside, along the sandstone ridge, a dedicated team of rangers are protecting another very special feature of Kinver Edge – its rare heathland habitat and the myriad of plant and animal species that live there.