The offers she received would have consigned her to a back-seat position not dealing directly with clients. Eventually she found her place as a lawyer in the Department for Education, where working arrangements were more flexible.
"If I was involved in a parliamentary debate on a non-working day, I was allowed to swap my days around," she says. "That was a formative experience for some of the work I have been involved here at the commission about diversity."
Although there are some "fantastic role models" of women and men working flexibly, there is still too little accommodation in the workplace, she argues.
"We need to make it easier for women to have families and go back into their professions in a seamless fashion."
After eight years in Whitehall, and by then working full-time, Ms Hilsenrath, from Hertfordshire, moved in 2008 to become chief executive of LawWorks, a charity which helps people find pro bono legal advice. Somehow she still found the time to publish e-novels under the name Jane Diamond.
She joined the EHRC as chief legal officer in 2014 and within 18 months was acting chief executive. She landed the role permanently last October and describes it as "the best job in the world".
Invaluable to her career was her experience as a co-founder of the Hertsmere Jewish Day School, and then Yavneh College in Hertfordshire. She had a son in each of their first intake.
"If you just stick to the day job, you don't learn as much as you can about life. Everything I learned subsequently about leadership goes back to that."
"I took my babies to school governors' meetings all the time," she says.
"I was trying to lead my life and that is the great thing about voluntary work. It is about keeping your mind going and making a contribution to the community, while having a family."
Since the Race Relations Act was passed in 1965, anti-discrimination law has greatly extended its reach. The EHRC's casework includes backing successful legal action last year against a pub which refused entry to Irish Travellers.
But the EHRC will often intervene before litigation, as last year when the rabbis of a Chasidic sect in London had threatened to bar the children of women who drove them to school.
The policy would be unlawful, the commission declared at the time.
More far-reaching was the Supreme Court ruling in 2009 that Jewish schools could no longer accept pupils simply on the basis of Jewish parentage, when race relations law effectively trumped any religious exemption.
Asked now if she would give her own opinion of the decision - she has been an admissions governor for HJDS - Ms Hilsenrath declines, but the commission will publish a report on religion under the law in the autumn.
One issue under discussion has been the higher threshold needed to prosecute religiously motivated crimes than racial ones.
"There is additional protection if it's racial than if it is religious," she says.
"Because Jews and Sikhs are defined as racial groups, they get protection, for example, that Muslims and Christians do not."
In a recent blog, Mrs Hilsenrath said she was appalled at the reported post-referendum rise in racist abuse and incidents, mentioning that one of her own employees was told to "go back" to her own country after a row in a car park.
Demanding as her role is, Ms Hilsenrath says "parenting is the hardest job". As well as four sons aged 17 to 22, she and her husband have a foster daughter of 18. "
The advent of my daughter in my life has been a great joy for us, and I hope for her. Fostering is something I'd certainly recommend."
