It coincides with the news that her most famous client, the Duchess of Cambridge, is expecting her third child next spring – and Cécile could not be happier – on both counts.
Her new flagship store, in Place Saint-Sulpice next door to Saint Laurent, is already attracting mamans-to-be who know the range from outfits worn by stars like Marion Cotillard and Anne Hathaway.
She is also looking forward to showing Kate the new range.
Séraphine achieved profits of £2.2million for the year to March 2017 and now, with 10 stores, including two in New York and four in the UK, she is eyeing other French cities.
“I was born in Paris, so the new store is a dream come true. However, it’s been hard.
“We already had a ‘shop-within-a-shop’ in the Paris Galéries Lafayette but that was arranged through our UK company. This time, I had to set up a French company: Not easy!
“The British have a positive attitude to business based on trust, so deals can generally move quickly, while the French are more suspicious and things take longer, especially now.
“You just have to respect their point of view and tread carefully – even if you are French!”
Cécile, 45, who is divorced with two teenage sons, learned to sew and developed a passion for fashion when her grandparents owned a fabric company in France. She moved to the UK with her parents, then returned to France to study for a business degree in Reims. Later, she moved to London, becoming the youngest account director in the history of advertising agency J Walter Thompson.
Having searched unsuccessfully for stylish maternity wear during her pregnancies, she spotted a gap in the market and started the business.
Her maternity jeans became a lifesaver for pregnant women used to ugly, baggy leggings.
“Creating a new fashion brand from scratch is a real challenge, but I believe in letting my intuition guide me. London is the best place in the world to find talent and do business. We employ brilliant young people from all backgrounds. I oversee the designs but have a team to produce and manufacture.
“My role is to use my experience to galvanise our export drive and keep everyone enthusiastic and happy, and to do the deals! Brexit is the perfect opportunity to show the world what we can do.”
Already a favourite with celebrities and models, Séraphine hit the headlines when Kate wore a fuschia dress for official pictures with Prince George.
Now that Kate is expecting her third child, Cécile is ready to present designs for official and private engagements: they must look good in photographs, but be practical.
“The stores are named for Seraphina, a guardian angel who is soft, gentle, but also independent and strong.
“That image fits well with maternity clothes. A woman is at her strongest during pregnancy: she has to be. The Duchess looks wonderful in creamy colours, but she also suits vibrant shades like that little pink dress. I love her attitude: she is so business-like.
“It will be winter during most of her pregnancy so warm coats are needed, but every woman who has had children knows the last month or two is when you feel hot and heavy, so it’s best to have lighter dresses under a coat and they mustn’t crease!
“Kate’s impeccable makeup, elegance, empathy and charm are skills she has learned. Believe me, attention to those details takes hard work.”
The Paris store also has baby clothes and accessories from shoes to belts and jewellery for non-pregnant customers. Prices range from €7 to €440..