I greet Emilia Fox by informing her that I now have the full set of Foxes, having previously interviewed cousin Laurence (twice), brother Freddie (in a car park in Belgium, if I remember rightly), father Edward and uncle James. "Oh, have you met Uncle Robert then?", she asks airily, as if we moved in similar circles. Uncle Robert is the theatre and movie producer, Robert Fox.
There's always one more, isn't there? Actually there are three more, if you count the latest cousins, Lydia and Jack, to enter what must be termed the family business.
Emilia Fox herself has, for the past 12 years, portrayed forensic pathologist Dr Nikki Alexander in the long-running BBC1 crime drama Silent Witness. She has taken a variety of other roles during this time, including two notable villains - the sorceress Morgause in BBC1's Merlin and a serial-killing clergyman's daughter in the 2007 TV drama Fallen Angel - but no one quite as authentically chilling as her latest part, as human trafficker Vanessa Hamilton in the new series of the Anglo-French thriller The Tunnel.
Chain-smoking cheroots, with scraped-back hair and thick black mascara surrounding eyes as cold as an empty grave, Hamilton is about as far from Nikki Alexander as you could probably get.
"Nikki is always on the quest for truth and justice, and Vanessa has absolutely no morals or goodness at all," says Fox. "She is someone who is shut off emotionally from the things that she does. A truly bad person."
The Tunnel is, of course, based on the Scandi-noir series The Bridge, in which Danish and Swedish police team up to solve a murder that straddles both jurisdictions - except here it's British and French detectives (played by Stephen Dillane from Game of Thrones and Clémence Poésy from Birdsong and In Bruges) uniting to fight cross-border crime.
"I'm a massive fan of The Bridge", says Fox. "So I was just delighted to be in anything that's in any way connected to that show.
"Coincidentally, I'd just been asked to be a patron of the charity Unseen, which aims to create awareness and offer help to the victims of trafficking and modern slavery. The true horror of Vanessa is that there are probably lots of people doing what she is doing."
The new series, subtitled Sabotage, links the abduction of a couple from their car on Eurotunnel's shuttle service and the downing of a passenger airliner in the Dover Strait, and was pushed back a week by Sky Atlantic due to sensitivities over the recent terrorist attacks in Brussels. I wondered whether Fox was consciously distancing herself from Silent Witness with such material, and had plans to leave a show that this year marks its 20th anniversary?
"No, not at all", she says. "I never consciously do anything with my career. I chose it for all sorts of other reasons."
Silent Witness still pulls in over nine million viewers an episode, extraordinarily healthy numbers in this age of promiscuous viewing habits. The show has the added advantage of being filmed just up the road from Fox's home in Acton, west London, which she shares with five-year-old daughter Rose and a live-in nanny.
Rose's father is the actor Jeremy Gilley - he and Fox broke up when Rose was still a baby - and she was previously married for five years to Jared Harris, Mad Men's Lane Pryce and the son of hell-raising screen legend Richard Harris.
"I'm quite lucky because with Silent Witness, Rose has been part of that family for so long," she says. "I was pregnant with her when I was still filming it, and the studio is only five minutes away from my house - so it means that more often than not I can do the school drop-off and get back for bedtime."
She even provides the charming mental picture of her father Edward, an actor known for playing debonair but still rather stiff members of the ruling class, getting down to Rose's level. "I can ring up dad and ask him if wants to hang out in the playground together and he enters into the spirit of it in his late 70s", she says.
The 41-year-old actress now counts among her personal friends some of the forensics advisers who work on Silent Witness, and has herself attended two autopsies. "The first one was when they asked me to do the job", she says. "It was of an older man in his 80s, so in a way it felt more natural.
"Nevertheless, I found it very thought-provoking. Is that it? You live your life and then you end up on a slab, the essence of you is gone ... there is literally a carcass there. I was really quite upset about it. I suppose the message of it is that you have to make the most of every second that you are here. And I got that message loud and clear because the next autopsy was a man in his early 20s."
And while we're on the subject of mortality, Fox recently filmed Mum's List, which is based on the best-selling memoir by Signe Green. Rafe Spall plays Signe and Fox plays Kate, a real-life couple from Somerset. When Kate was diagnosed with incurable breast cancer she spent her last days writing down her thoughts and memories to help Signe create the best possible life for their two sons.
"When people ask 'did you take Vanessa Hamilton home?'', the answer is, no I didn't," says Fox. "But I found it much harder to say goodbye to Kate during filming. I found that very affecting because I'm a parent. I feel very emotionally connected to that story."
Just before filming The Tunnel on the Kent coast, Fox was nearby in Margate shooting The Carer, in which she played the strong-willed daughter of a grand but dying Shakespearean thespian (Brian Cox).
In many ways, hers is an enviable career, anchored for seven months of the year by Silent Witness, but providing plenty of room to experiment, sometimes even playing characters whom Dr Nikki's fanbase might find repugnant. Does she worry that they might?
"I really hope they understand it''s a drama and not a documentary, and that I'm not Vanessa Hamilton," she says. "But if I worried about that through all the work that I ever did, then I would only ever play myself or characters like Nikki Alexander, and that would be incredibly limiting."
Quite so. Now where do I find Robert Fox?
The Tunnel begins on Tuesday on Sky Atlantic at 9pm