Who Do You Think You Are: Researching celebrities' family histories
The most exciting time for me on Who Do You Think You Are? is always the last days in the run up to transmission of the first episode. This year's 10-part series has taken over a year to make, so being able to see the finishing line is a moment to cherish and enjoy.
As the executive producer on the series, I'm responsible for every aspect of the production - from liaising with the celebrities taking part, to overseeing the research for each episode, to approving scripts, to viewing the programmes as they're being put together in an edit suite.
The great thing about WDYTYA is that every episode is completely different - and when we start researching stories, we literally have no idea what we might unearth.
In fact, it's finding a crucial document or a fantastic eyewitness that makes the job as brilliant as it is.
WDYTYA is now in its eighth series so this year we were determined to make the casting feel fresh and new. I'm hugely proud of this year's line-up and hope you're all excited about some of the names coming up over the next 10 weeks.
And the rest of the cast is a roll call of familiar names, whether that's because of the music they've made, like Robin Gibb from The Bee Gees, or because of their performances on some of the BBC's biggest shows, like Len Goodman from Strictly Come Dancing, and Emilia Fox.
Casting the series is always a really exciting part of the process. We're exceptionally lucky that lots of people really want to explore their family history - and often people come to us with something particular they'd like to discover.
The hard part comes when the research begins.
Before we commit to making an episode with a particular celebrity, we do around three months of dedicated research - first building their family tree, then trying to get all the documents available relating to their ancestors.
This is a painstaking task, which often leads to dead ends and brick walls.
Sometimes, we're extremely lucky - a vital clue will simply fall into our hands. But in some cases we have to make the difficult decision to stop the research and let the celebrity know that we won't be able to make the programme.
Of course, we provide them with all the research we've accumulated - but as far as the series goes, that's the end of the story.
This means for a run of 10 episodes, we research around 30 people.
June Brown talks about her life, career and family
I have to say, though, that at 84 June has remarkable energy, boundless goodwill and a really naughty sense of humour.
Usually, the participants go on the journey alone, with just the crew and the director for company. June was accompanied by one of her daughters, so it really was a family adventure.
WDYTYA can be very emotional for the celebrities taking part.
Emilia Fox was eight months pregnant when we filmed her episode and we knew that one of the stories she would encounter involved a stillbirth for one of her ancestors. We were hugely aware of how emotional - and difficult - this might be for Emilia.
Though we don't reveal anything about what's coming up to those taking part, we do always warn everyone that history has a habit of taking surprising twists and turns - and that they might not always like what they find.
The directors on the series are all hugely experienced and are especially good at dealing with these very raw situations. We never shy away from an emotional reaction, but we always make sure it's not mawkish or sensationalised.
There is a major revelation in JK Rowling's film, which could have caused her and her family considerable discomfort.
I discussed this particular revelation - and the way in which it would be revealed to Jo - with the director and series producer many, many times in the months leading up to filming.
We decided in the end that it had to be as real as possible - after all, it's Jo's journey and not ours.
We're really proud of the resulting scene, and the rest of the film, so it would be great to hear what everyone else thinks. It's certainly a heart-stopping moment and one I'll always remember from my time on the series.
Perhaps the most difficult experience I've had on the series was during last year's run when our research team discovered that Alan Cumming's maternal grandfather had accidentally killed himself playing a game of Russian Roulette.
Alan Cumming discusses his maternal grandfather
Alan's family weren't aware of this - knowing only that he'd died in a "shooting incident".
We, as a team, felt an enormous responsibility to Alan and his mum, but we also knew that they really wanted to know the truth.
The moment of discovery for Alan was, I think, hugely shocking, disturbing and upsetting - but ultimately brought his family the knowledge they'd desperately craved.
Luckily, it's not always tears and tragedy. It's fantastic to feature stories of great triumph and heroism.
Larry Lamb's film this year is very special to me as we managed to unite Larry with a relative he never knew he had - on the other side of the world - and there's real humour in this year's series too.
Alan Carr brings a fantastic sense of fun to his episode - even when there's bad news, he just keeps laughing.
So, with 10 extraordinary stories which cover four centuries, three continents and a year of research, filming and editing, I can't wait to hear what you make of the new series - and for everyone to discover the secrets and revelations that we've had to keep to ourselves for the past year.
Tom McDonald is the executive producer of Who Do You Think You Are?
Comments made by writers on the BBC TV blog are their own opinions and not necessarily those of the BBC.