Lowther-Pinkerton said he was in his mid-20s before learning that his mother Sue had worked for MI5 after World War II, a secret she kept from her children for decades.
A stray remark during a documentary about the Cambridge spy ring exposed her insider knowledge: Sue dismissed claims that former MI5 chief Roger Hollis was a Soviet agent, but refused to say more.
Sue’s wartime and intelligence service stretched from the ATS in 1942 to Army intelligence in Singapore and MI5 work in London after 1951, before she left the agency in 1956 to raise a family.
That hidden history became the basis for Lowther-Pinkerton’s debut novel, "Beyond the Edge of Light," whose central character was modeled on Sue, who died in 2023 at age 99.
Lowther-Pinkerton, a former private secretary to Prince William and Prince Harry from 2005 to 2013, said the strong women in his life shaped his writing, with his mother at its center.