For one thing, it is immaculate. "I'm fastidious," she admits, miming obsessive wiping of kitchen surfaces. She is also, "a very literal person. If someone says 'play that staccato', you won't hear it played shorter." Then, of course, there is her double bass in the front room - the oversized instrument, "a man's instrument" as she was told when she started out, seeming cartoon-ish here, despite the tall ceilings of her elegant Victorian terraced semi.
After you have taken in Nwanoku's jaunty, jewel-coloured afro, and the surprise of her bright turquoise eyes, the most striking thing about her is her energy. She is, she says, only five feet tall. But she is a woman clearly driven by a relentless, indefatigable energy.
"People are shocked how much I get through in a day," she says. Her engine is curiosity, coupled with a healthy competitive streak - both of which have been her defining characteristics since she was a child.
Nwanoku's talent and determination have carried her to the very heart of the British cultural establishment, but it's been a long and rather improbable journey to get there.
She was born in Fulham, London, the eldest daughter of an Irish nurse and Nigerian medical student. Mixed race couples were an anomaly at the time and her parents faced enormous prejudice, both from society and closer to home, within their extended family. They were economic migrants to the capital of the British Empire at a time when landlords routinely posted signs reading "no blacks, no Irish, no dogs." But her parents' love flourished and endured for 50 years until they died. It was through witnessing her parents' bond, that Chi-chi's own iconoclasm was formed.
She clearly adored them. Her father died 12 years ago and her Mother two years later, and even now, when she talks about them, tears flow. "I get upset when I talk about my parents," she says. "I miss them so much... I was completely demented when dad died and my mother went downhill soon after." They were, she says "happy people," and the house she grew up in a joyful one.
"They loved each other so much and they loved us so much. I think I've always been filled with this sense of justice, because they both felt the strong arm of injustice."
She relishes telling the story of how they met, at a dance in the Hammersmith Palais, where Margaret and her friend, disgruntled that none of the men there had asked them to dance, were in the cloakroom about to leave, "when my dad walked in with an African friend. A minute later and they would never have met. My father just took one look at her and said, 'where are you going?' I was born a year later. They never parted from that moment. It was literally love at first sight. My mother had never even spoken to a black man before. I mean, he was a great dancer. And every photo that you see of them, they are dancing. They danced all through my life."
Chi-chi herself hasn't been quite so lucky in love. She got married, aged 30 to Tim Hugh, who is joint principle cellist of the London Symphony Orchestra. They have two children but divorced eight years later. "We both come from big families. Getting divorced, neither of us were used to that. We're both used to parents who stuck together, so it was hard to go through that. It was painful," she admits. The pair remain firm friends however, and are deeply involved together in the lives of their son and daughter, who are in their late 20s.
Chi-chi is someone who knows instinctively the value of family bonds. She was not yet a year old when her younger brother was born, and twins followed swiftly after. Then there were two more sets of twins who tragically died, before the smallest sister arrived. At one stage, there were four siblings under the age of two-and-a-half. It must have been chaotic, but they were "an incredibly close family." This was partly because they were isolated together - far from Michael's sprawling Nigerian family, and distanced from Margaret's Irish one.
Chi-chi's mother was born on the Limerick/Tipperary border and grew up in Thurles. When she left Ireland, she left behind "a very, very hard, hard life" and a childhood during which she had a very difficult time. Chi-chi skips over the particulars, saying instead she is full of gratitude and admiration for her mother - who was strong enough to keep the impact of those traumas contained, never allowing the taint of them to impair her relationships with her own family.
She was, Chi-chi says, an "incredible woman. She was a disruptor from day one... She was asking questions from day one in a Catholic school. And then she would be beaten for that. She asked questions all the time, she challenged everything."
To her mother, the new life she made with her smiley African husband must have seemed a refuge. And it didn't matter that "there was very little money when we were growing up." The family ate things like bread and dripping and pig's trotters at home, and the five kids looked forward to the free school lunches at their local grammar school, but "we didn't feel poor, because our lives were full and rich and creative. We didn't have toys but we made our own games and we had much more fun than most kids. There was never a dull moment in our house."
Theirs is a classic tale of immigrant striving and grit. In order to pay for music lessons for her children, Margaret went off to work at night. The children were never explicitly pushed, but it was clear to all of them that expectations were high. "As a black child, or a mixed race child, I don't think any child of colour growing up in a country like this with half-decent or self-respecting parents, I think every single one of us is told, "Whatever you want to do in life, it's not going to be enough to be as good as the next person. You have to be better. So there has always been that underlying pressure."
Athletics was Chi-chi's first love. She was just eight when she was spotted on a running track by a sprint coach who talent-scouted her with a mind to grooming her into an Olympic champion. "That coach, he'd had meetings with my parents, my teachers, my headmaster, before I knew anything about it," she says. For almost 10 years, she trained intensively. "I liked winning races. I didn't know that at the time, but it just gave me huge pleasure. I think I was born a performer. I performed on the track, that was my first stage, if you like."
It all came to an abrupt end however, when one day she volunteered to play in a women's football match and a freak accident - she dislocated her knee after a rough tackle - extinguished her dreams in seconds.
She still gets upset about it today. The ghosts of a lifetime of "what ifs" still linger. "There are still tears for me when I watch athletics," she says. "I am now 60, and I retired at the age of 17. And the last official times I was running were 11.8, and getting faster all the time. Now, I'm watching the Olympics, and OK, the women are now getting down to 10-something, but most of them are around the late 11s."
It's rare enough to have one burning passion, one outstanding talent. But Chi-chi had another up her sleeve. She had always been obsessed with learning music, taking up the recorder as a very young child with almost puzzling dedication, and pestering her neighbourhood friend's older brother to teach her to play the piano. As soon as he had, she turned up at his house every day to play - to the extent that eventually the boy's mother wheeled the instrument down the street and gifted it to her.
She had the luck too to have two enlightened mentors - the headmistress and the head of music at her grammar school put their heads together after her accident and came to her saying, "Chi-chi look, you are by far the most musical person in the whole school. You could have a career in music but you don't play an orchestral instrument... we completely believe that you could have a career as a professional musician if you took up an unpopular instrument." It was in that moment that her love affair with the double bass was born.
She hasn't looked back since. She studied at the Royal Academy and soon after became a classical performer of international reknown, playing as principle soloist with the world's best orchestras. She also presents a show on BBC Radio 3. Her achievements are too hard-won for her to be coy about them. There is no nonchalance as she reminds me that her full title is Chi-chi Nwanoku MBE (she received the honour in 2001).
She beams with pride too, when she talks about her most recent project - the 'Chineke! Orchestra', Europe's first black and ethnic minority orchestra, which has been taking the classical music world by storm. Chi-chi knows that her career would never have happened were it not for key people who intervened to encourage and channel her talents. "If I was the child I was then, now, I would be one of those children who would be told I've got ADHD and I need drugs to control me in the classroom. I was bouncing off the walls, I had more curiosity and energy than was good for me. I needed to know everything, I wanted to be in everything. And I was fascinated by everything that was going on inside the classroom and outside the classroom."