Dr Thomas Dixon brings his major new series on the changing face of friendship to a close with a look at how the old and the young are navigating their friendships today through technologies old and new, and at how friendship might look in the future.

Episode 15: The Lonely Cyborg

A group of Birmingham schoolgirls prove themselves thoughtful and self-aware about how to conduct their friendships online and about the differences between online and face-to-face friendships. Professor Deborah Chambers, an authority on social media and personal relationships from the University of Newcastle, confirms that fears about children's online friendships with strangers have been exaggerated.

At the other end of the life-span, Thomas Dixon speaks with the writer Penelope Lively about friendship in her ninth decade, and about why she likes to consider herself part of "the landline generation".

Closing the series, Thomas Dixon emphasizes the importance of physical touch and presence for friendship, and presents a final montage of the voices which have featured throughout the series, sharing stories of their own friendships.

Producer: Beaty Rubens.

Dr Thomas Dixon brings his major history of friendship up to the 1970s, when gender politics began to change friendships once again, and considers how popular culture both reflected and influenced this change.

Episode 14: Families of Choice.

Professor Barbara Taylor shares with Thomas Dixon her personal memories of how the second-wave feminist movement of the 1970s altered women's friendships in the way that Mary Wolstonecraft had discussed right back in the eighteenth century.

Thomas Dixon also explores the growing freedom of gay men and lesbian women to establish their own "families of choice".

And - somewhat excitedly - he debates with the cultural critic Matthew Sweet how television reflected friendships between men. While Thomas confesses to an erstwhile love of the phenomenally successful American sit-com, Friends, Matthew Sweet makes an expansive claim for British television's The Likely Lads, comparing the depth of Terry and Bob's friendship to that of Tennyson and Hallam.

Meanwhile, slightly extending a quotation of the 17th Century poet, George Herbert, Thomas declares: "David had his Jonathan, Christ his John, Eric had his little Ern, Ant his Dec."

Producer; Beaty Rubens.

Dr Thomas Dixon continues to trace the changing meaning of friendship over the last five hundred years.

Episode 13: In Need, In Deed, By Post

Mass Observation and the archive of the Co-Operative Correspondence Club provide intimate evidence for friendship during the Second World War.

Dr Clare Langhamer discusses how, in 1935, one lonely mother in County Wicklow began a correspondence network that continued through to the 1990s, long preceding today's MumsNet and NetMums.

She also shares some revealing evidence from the vast Mass Observation archive at the University of Sussex about how women's friendships were affected by their war-work.

Thomas Dixon also considers how men on active service formed new bonds across the class divide, and, in one extraordinary case from the BBC Sound Archive, not only with other human beings: "I have a passion for tanks," begins Captain Michael Halstead's account of life on the front line.

Producer: Beaty Rubens.

Continuing his history of friendship over the last five hundred years, Dr Thomas Dixon explores how friendship was changed by a new form of technology and a new type of science in the early years of the twentieth century.

Episode 12: The Suburbs of the Heart

Just as the internet has been seen as an enemy of friendship, so the new technology of the early twentieth century - the telephone - was initially viewed with mistrust. Magazines and newspaper articles listed it along with the telegram and the motor car as potentially detrimental to the art of friendship.

One author wrote: "we live, alas in the suburbs of each other's hearts".

Meanwhile, as the real suburbs were extended, the new science of psychology began to advise lonely city-dwellers on how to form new alliances and friendships.

Dr Thomas Dixon hears from Professor Mark Peel about the impact of urbanisation on friendship, and is won over by his surprisingly passionate defence of Dale Carnegie's often mocked best-seller, How to Make Friends and Influence People.

Producer: Beaty Rubens.

Dr Thomas Dixon brings his timely new history of the changing face of friendship into the era immediately after the First World War, when the international friendship movement flourished.

Episode 11: Testaments of Friendship

At the centre of this episode is the story of Vera Brittain, author of the ever-popular memoirs, Testament of Youth and Testament of Friendship. Thomas Dixon traces Brittain's life through her pre-war loves, the heart-breaking war-time losses of her brother, her two closest male friends and her fiancee, and her post-war friendship with the writer, Winifred Holtby.

Thomas Dixon hears from Brittain's daughter, Baroness Shirley Williams, about her mother's passionate belief in the ability of women to sustain profound friendships even during a period when they were frequently depicted in films, books and newspaper articles as being hostile to one another.

He also speaks with Professor Seth Koven about Muriel Lester, whose friendships both with a poor East End girl, Nellie Dowell, and with Mahatma Gandhi, represented a drive for international peace and reconciliation after the horrors of the First World War.

Producer: Beaty Rubens.

Dr Thomas Dixon presents a timely new history of the changing meaning and experience of friendship over the centuries

Episode 10: A Battalion of Pals

Dr Thomas Dixon tells two contrasting stories for this examination of the impact of World War One on male friendship.

He begins and ends with the pacifist Bloomsbury Group, focusing on E.M Forster and his famous remark, "If I had to choose between betraying my country and betraying my friend, I hope I should have the guts to betray my country". Dr Matt Cook places this remark - shocking at the time - in the context of Forster's hidden sexual orientation.

Forster began his masterpiece, A Passage to India, before the war, in optimism about the possibility of friendships and love across the nations. As Dr Santanu Das explains, he completed it, after the War, in a far bleaker mood.

Meanwhile, amongst the less highly educated classes, groups of work-mates were being conscripted into the army. Thomas Dixon explores this new role for friendship - as a recruiting sergeant - and its tragic consequences.

Producer: Beaty Rubens.

Dr Thomas Dixon presents a timely new history of the changing meaning and experience of friendship over the centuries

Episode 9: Comrades and Lovers

Drawing on the intriguingly ambiguous relationship of Frances Power Cobbe with Mary Lloyd and the more open relationship of Edward Carpenter with George Merrill, Thomas Dixon explores the Victorian borderland between Platonic friendship and homosexual love.

Professor Barbara Caine discusses Frances Power Cobbe, the largely forgotten Anglo-Irish feminist and journalist, who wrote articles with titles such as, "The Woman Question", "What Shall We Do With Our Old Maids" and "Wife Torture in England". She explains how Cobbe reclaimed friendship for women after centuries of classical and renaissance assumptions that only men had a true capacity for it.

Dr Matt Cook tells the story of Edward Carpenter, whose own unconventional lifestyle and 1908 book, The Intermediate Sex, brought homosexual love out into the open and even introduced the contemporary notion, celebrated in tv series such as Will and Grace, of women enjoying having a "gay best friend".

Producer: Beaty Rubens.

Dr Thomas Dixon presents a timely new history of the changing meaning and experience of friendship over the centuries

Episode 8: Darwin's Best Friend

Charles Darwin loved his dog and praised her in letters to friends as "the beloved and beautiful Polly". He believed that dogs shared qualities such as a sense of shame, honour and affection with humans, and wrote about them in The Expression of the Emotions in Man and Animals.

It was in this era that dogs were, for the first time, given the title of "man's best friend".

Thomas Dixon traces the impact of Darwin's own relationship with animals on his theory of evolution, and compares it with his ideas about other, "savage" human beings, whom he encountered in Tierra Del Fuego, during his trip on the Beagle.

He also considers Darwin's deeply affectionate and intimate friendship with his fellow-scientist, Joseph Hooker, at a time when it is often believed men were disinclined towards displays of emotion.

With contributions from Emma Townshend, author of Darwin's Dogs, and Hooker expert Dr Jim Endersby.

Producer: Beaty Rubens.

As the nature and depth of our friendships comes under scrutiny in an era of Social Networking, Dr Thomas Dixon presents a major new history of the changing meaning of friendship over the centuries.

Episode 7: Education of the Heart

Today, we tend to view friendships among children as a good thing, but in the 18th century, improving "conduct manuals" tended to warn children off friendship, seeing it as fraught with danger. In an era of large families, friendships among siblings were considered far safer.

Thomas Dixon learns from the distinguished expert on the history of childhood, Professor Hugh Cunningham, how the reduction of family size and the spread of mass education in the 19th century began, inevitably to challenge this notion.

But the idea of the dangers of friendship for children persisted.

Thomas Dixon goes on to explore with children's literature specialist, Dr Matthew Grenby, how the classic school stories of the 19th century - from Matthew Arnold's Tom Brown's Schooldays to Angela Brazil's A Fourth Form Friendship - continued to provide moral advice about friendship, buried within their depiction of algebra, lacrosse and midnight feasts in the dorm.

Producer Beaty Rubens.

As the nature and depth of our friendships comes under scrutiny in an era of Social Networking, Dr Thomas Dixon presents a major new history of the changing meaning of friendship over the centuries.

Episode 6: Felons and Oddfellows

Thomas Dixon traces the idea of friendship as a form of practical self-help back to the Friendly Societies of the 18th and 19th centuries. At their peak, there were 9000 of these grass-roots institutions - many with quaint, archaic names, such as The Manchester Unity of Oddfellows - and it is estimated that 40% of the adult male population belonged to one - mobilising the power of friendship in a sort of forerunner of the Welfare State.

The importance of the idea of friendship emerges through the colourful vocabulary of friendship in the period - from cronies, trumps and bloaters to culliles, marrows and rib-stones, and the more familiar, chums and pals.

With contributions from Dr Helen Rogers and Professor Hugh Cunningham.

Producer Beaty Rubens

Dr Thomas Dixon is Director of the Centre for the History of the Emotions at Queen Mary, University of London, with a particular expertise in the histories of emotions, science, philosophy and religion.