Ana Patricia Botin, CEO of the UK unit of Spanish banking giant Santander, ranks behind only Queen Elizabeth II and Home Secretary Theresa May on a list of Britain's 100 most powerful women.
Elizabeth, 86, took the top spot in a poll commissioned by BBC Radio 4 show "Woman's Hour."
Following Botin on the list are Baroness Brenda Hale of Richmond, a Supreme Court judge, and Elisabeth Murdoch, the chairman of Shine Group.
Author J.K. Rowling, creator of the "Harry Potter" saga, is in 13th place and the deputy first minister of Scotland, Nicola Sturgeon, comes in at No. 20.
Despite her enormous popularity, the name of Kate Middleton, duchess of Cambridge and wife of Prince William, was not included.
"Most women on our list have power because they have reached a place where they have control - of policy, of direction, of influence, of staff," newspaper editor Eve Pollard, a member of the panel that assembled the list, said.
"Inevitably not everyone will agree with our 100. There are some omissions. For example, we had long debates about the Duchess of Cambridge. Is she influential? Hugely. Is she powerful? Not yet," Pollard said of Middleton, now pregnant with a future king or queen.
Runners-up to the top 20 include Clare Foges, chief speechwriter for British Prime Minister David Cameron, and music superstar Adele.
Less than a third of Britain's most influential positions are occupied by women, according to data compiled by the BBC. EFE