Over the past 14 years, JK Rowling's Harry Potter novels

have sold almost 450 million copies,

transforming her from struggling writer into the most successful author in the world.

But Jo has been unable to share her success with one of the people she cared about most.

Mum died when I had just started writing Harry Potter.

It's a real regret actually that I never even mentioned it to her,

that she died without knowing anything about something so huge.

She knew I had literary ambitions

but she never knew that I'd had the idea of my life to date.

My mother's maiden name was Anne Volant,

she was a quarter French and she was very interested in her French roots

but never had a chance to explore them.

So the huge motivation in looking into my family history is my mother.

It's very much bound up in, in that loss.

Jo Rowling lives and works in Scotland

but can trace her French roots back three generations.

My mother's father's father, Louis Volant married an English woman

and I know the marriage failed.

I know something about his war record.

He was very brave in the First World War.

I don't know all the details but he was awarded the Legion d'honneur.

In 2009, Jo herself won the Legion d'honneur,

France's highest honour, for her services to world literature.

I made my speech in French and it was an opportunity to speak about Louis.

It was one of the most meaningful awards that I've ever received, because of that family connection.

But I don't really know where he came from,

I don't know what kind of family he came from

and I don't know anything at all about the generations behind him.

Jo has decided to start her search into Louis Volant

and her French roots in the Scottish capital.

I'm going into Edinburgh to see my Aunty Marian,

who's staying with friends here and she's my mum's big sister,

and she's the last link to the French family.

She was born a Volant, that's her maiden name.

DOORBELL RINGS

- Hello, my darling! - How are you?

Lovely to see you.

Marian Fox is Jo's maternal aunt, and the daughter of Stanley Volant,

the youngest of four children born to Jo's great grandfather,

Louis Volant and his wife, Lizzie.

Marian has brought the family's collection of letters and photos to show Jo.

- I'm very excited. - This is the famous wedding album.

So this is your wedding to Les.

My wedding to Les, me with my 18-inch waist.

Your 18-inch waist. Tiny.

- There's Mum. - Ahh.

We had that dress for dressing up, it was pale blue.

- That's right, yeah. - Ahh.

This is Lizzie, your great grandmother.

- She was lovely. - Was she?

- She taught me my prayers, cuddled me, she was a natural grandma. - Ahh.

She was really gorgeous.

So Lizzie married Louis.

Have you found Louis at all?

Yes, there's some here.

I have a photo.

- Oh, I've never seen that before. - He's handsome, isn't he? He's gorgeous, isn't he?

This is Louis' good conduct certificate.

Right. This is from National Service, is it?

- Yes, and look at this, Jo. - Ah.

- Was he born on your birthday? - He was born on 31st July.

Exactly the same day, yeah.

Oh, my God.

How bizarre. Same date as me and Harry Potter.

That's right.

And he was born in Paris in the 10th arrondissement. Wow.

I think this is a photo of his mother.

- Oh, my goodness. - And her name, would you believe is Salome Schuch. - So... - Very strong-featured lady.

What do you know about her?

- Very little. Just that she grew up in the countryside in France. - Right.

So when did Louis arrive in England

and why did he come to England?

We know he came over in the 1890s

and he worked over here as a waiter

in places like the Savoy.

Classy joints.

Oh, classy joints, classy joints.

And that's where he met Lizzie

- who was working as a nursery maid for a family off Marble Arch. - Oh, wow.

Have a look at these.

They're all letters that Louis wrote Lizzie, over the years,

right from when they first met.

- Oh, wow. - They made me cry, they are so lovely.

- "Dearest Lizzie." - Everything is, my dearest Lizzie.

This was written about 1896.

- Right. - And he was having to go back to Paris to do his National Service.

"Now, darling, just have a little more patience.

"I think this shall be one of the last letters I am writing to you,

"so with all my fondest love and kisses to my dearest Lizzie, from your own forever Louis.

"PS Write soon, Liz, time will fly now. Ta-ta, my love."

Oh, it's lovely, isn't it? It's so sweet.

And that is Lizzie and Louis' wedding photo.

- Well, you can see what they saw in each other. - Oh, yes, yeah.

She was 25, he was 22. So he was very young, wasn't he?

Very young.

Now this one is the first family baby photo taken,

when Marcel was born, in 1901 I think it was.

Right. It's actually very touching

- cos you know the marriage didn't work out. - That's right, yeah.

So when did Louis leave the family?

I don't know. It was always a bit of mystery.

Louis had gone back to France for some reason or other

and Lizzie wouldn't go over and join him,

- she wouldn't pack up and go to French. - Right. - So they split.

- After that we haven't got any family photos. - Yeah.

- We've got this, from the First World War. - Oh, my goodness. - Yeah, this is... - His identity card.

Wow. Wasn't there a photograph of him wearing his Legion d'honneur?

- No, this was the only thing from his effects that we found. - Oh.

The button ball badge of the Legion of Honour, but not the medal.

Isn't that wonderful?

Gosh.

I would love to know what the citation was for him being awarded that medal,

because I feel he did something very brave and sadly we don't know what it was.

- And I'm proud of him. - Yeah, me too.

Wow.

And where is he buried?

- I don't know where he's buried. - We don't know?

I don't know anything else cos there was no funeral service anybody attended that I heard of.

And there's nobody to ask any more.

- I'll put these back, Jo. - OK. - I want you to take them with you. - Ah.

- Look after Louis and Lizzie for me. - I will really. Thank you so much.

- I'll look after them. - Thank you.

I feel this weird pull towards Louis.

He left France to go to London,

a massive city

that's also a foreign city, so he's an immigrant.

That's very gutsy.

And then I found the letters so moving,

this very young man writing to his English girlfriend.

And Marian's told me he was a waiter and he worked at the Savoy

so I'm going to London.

Jo's great grandfather, Louis Volant, arrived in London in the 1890s

and worked in the city as a waiter both before and after the First World War.

Jo has come to the famous Savoy Hotel on the Strand

where Louis worked in the 1920s.

She's come to meet social historian Constance Bantman,

who's been researching Louis' life in London.

- So we are here. - Yes. - At the River Restaurant. - Yes. - At the Savoy,

which is where Louis worked between 1919 and 1927

and this is the restaurant in action.

Wow, I love this, it's so 1920s, it's so glamorous.

It was one of the best, if not THE best restaurant in the whole world.

- Wow. - And Louis was head wine waiter. - He was head wine waiter? - Yes. - Oh, Louis!

And he actually got an award for it, a French award,

called Chevalier du Merite Agricole.

- You're joking? - No, not at all. It's a very prestigious distinction.

- And this was given to him in 1922. - And here's his title in French.

"Chef du service des vins au Savoy Hotel."

Fair play to him, for a working class Frenchman who's come to London,

- he's certainly risen in his profession. - Absolutely.

We are extremely lucky in that the Savoy keep an archive of their former employees

and this is his card.

Oh, my goodness. Louis' card.

And the card contains previous employment history.

Louis' employment card reveals that to get to the Savoy

he had worked his way up

through the ranks of his professional since his arrival in London in the 1890s.

Political instability in France and cheaper cross channel transport

encouraged many young French men and women to seek work in the English capital.

By the turn of the century, there were tens of thousands of poor French immigrants

crammed into a part of Soho known as La Petite France.

Many sought work in the city's flourishing restaurants.

Louis' card records that he was taken on as a junior waiter

by the fashionable Princes' Restaurant in 1899.

This is the Princes' Restaurant. You can see very, very rich, very opulent surroundings.

Wow. Where is this?

- This is just off Piccadilly. - Oh, really?

It was a very nice place run by French people.

Would he have made more money here than he would have done in Paris?

Yes, here a French waiter had this immense cache.

- So these places were looking for Frenchmen. - Exactly.

The Princes' Restaurant was catering to the theatre crowd so it closed

at impossible hours and this would have been a demanding job.

Yeah. I've got this letter and this is from,

it's headed the Princes' Restaurant.

He's writing to his wife, Lizzie,

she's gone back to her parents' house in Norfolk

and he says, "You asked me to try and come over next Sunday, indeed I believe you struck it unlucky

"for we have a dinner of 60 Frenchmen and they have got a licence,

"so it's no use thinking about it for a moment."

- Oh. - So he couldn't see his wife, because he had to work late.

Yes. And that's obviously one of the striking features,

- it was a hard life. - Yeah.

Louis would have been working until two or three, six days a week.

Oh, my goodness, right.

Yes, very, very difficult lifestyle

and he earned probably about 40 shillings a month,

which works out to be about £80 in contemporary terms.

And by the time that letter was written, he was supporting a wife and child on that as well.

Exactly, and we can imagine the strain.

There was not much time for married life.

- If we look at the following census in 1911. - 1911. - You see there.

So we've got, Lizzie is listed first as wife

and then that's been crossed out and put head, as in head of the family.

So the marriage had already broken up in 1911.

And Stanley, my grandfather, was only one.

Oh, that makes me feel really tearful.

And so he'd gone.

And here he is. Louis Volant.

He's 33, he's still married but they've separated.

He's now living in 6 Upper James Street in one room. That's so sad.

I find what he did, coming across from France as a very young man

and then working his way up to pretty much the head of his profession,

admirable, just so admirable.

But when I saw the census where they were living apart,

I felt like it was happening now

and I think the most poignant moment of all

was her writing in "I'm a wife" and someone else crossing that out,

no, you are now the head of the family.

And then shortly after that, 1914, Louis was off to war.

Three years after the break-up of his marriage,

and 20 years after his arrival in England,

Louis Volant was called up to serve in the French Army

at the outbreak of World War One.

I know that he received the Legion d'honneur

for his actions in the First World War,

but I don't really know what happened to him.

Jo has decided to travel to Paris

to discover how her great grandfather became a war hero.

Among the letters Marian gave her are some that Louis wrote

to his estranged family during the war.

"Dear Lizzie and children, hope you're all getting on well.

"No change here for me, still it's all a case of luck.

"Love and kisses to all,

"from Papa. 1915."

Which makes him 37 which is quite, quite old to be going off to war.

Actually in that photograph I think he looks older than 37.

It says he was an interpreter and there's various stamps

but really nothing else really tells me much more about him or what he got up to.

To see if she can find out why her great grandfather was awarded

the Legion d'honneur, Jo has come to the national archives in Paris.

The archives were established in 1808

and store the most important documents of the French state,

including a record of every recipient of the Legion d'honneur,

France's highest decoration.

Claire Bechu is the deputy director of the archives.

This is incredible.