By . Harriet Arkell . The woman who wrote Harry Potter has admitted she will 'never, ever top' the successful series that made her a multi-millionaire. Author JK Rowling, 48, said that the 'unexpected' success of her children's books had brought her 'money beyond my wildest dreams', which was 'marvellous and liberating'. But she said that three years after the first book, Harry Potter and the Philosopher's Stone, was published, she knew she would never write anything as good. JK Rowling, worth an estimated £1billion, says she knew in 2000 she would never beat her Potter success . The first and second Harry Potter novels were published in 1997 and 1998 - there are now seven in the series . In an interview with Sky News the writer, who lives in Edinburgh with her husband, Neil Murray, and three children, said: 'By 2000 I knew perfectly well that I will never top Harry Potter -  I knew that before the series ended. 'So, what do you do if you've had that kind of success that you've never expected?  Well you can go one of two ways. 'You can think: "Oh no how dreadful, I'll never, ever top that", or you say say: "How incredibly marvellous and liberating, you know, that I made money beyond my wildest dreams, I can affect issues that I really care about. '"But what do I love doing?  I love writing, so clearly I'm going to continue to write." 'But I don't know.  I absolutely don't sit around and think I must now write a THIS kind of novel to prove that I can write it, because I always did write what I wanted to write and I will continue to do that.' The author, who has said she was 'as poor as it's possible to be' when she wrote the first Harry Potter novel as a single mother who would have just one Rich Tea biscuit for dinner, has made an estimated £1billion fortune from her books, which were also turned into films. Philanthropy: The author was publicising her Lumos charity, set up to fight children being institutionalised . The first Harry Potter was made into a film in 2001 starring Rupert Grint, Daniel Radcliffe and Emma Watson . Family: JK Rowling, 48, lives in Edinburgh with her doctor husband, Neil Murray - they married in 2001 . She published her most recent work, crime novel The Cuckoo Calling, in April this year under the pseudonym Robert Galbraith.  After Rowling was revealed as the true author, sales rose by 4,000 per cent. Rowling's revelations came during an interview to publicise her charity Lumos, which she set up eight years ago to fight the institutionalisation of children. The author, who is said to have given millions to charity, said: 'There are 8m children globally being raised by institutions and everything we know about institutionalisation tells us it's harmful to children's physical and mental health. 'To take a child from their family...it's about the worst thing you can do to a child... That's what we're working to end.'
Author worth £1billion says she knew in 2000 she'd never beat the series .
Rowling, 48, said children's books meant 'money beyond wildest dreams'
She said it was 'marvellous and liberating' but still wanted to keep writing .
Seven Harry Potter books have sold more than 450 million copies globally .
Mother of three, who lives in Edinburgh, set up Lumos children's charity .
By . Harriet Arkell . The woman who wrote Harry Potter has admitted she will 'never, ever top' the successful series that made her a multi-millionaire. Author JK Rowling, 48, said that the 'unexpected' success of her children's books had brought her 'money beyond my wildest dreams', which was 'marvellous and liberating'. But she said that three years after the first book, Harry Potter and the Philosopher's Stone, was published, she knew she would never write anything as good. JK Rowling, worth an estimated £1billion, says she knew in 2000 she would never beat her Potter success . The first and second Harry Potter novels were published in 1997 and 1998 - there are now seven in the series . In an interview with Sky News the writer, who lives in Edinburgh with her husband, Neil Murray, and three children, said: 'By 2000 I knew perfectly well that I will never top Harry Potter -  I knew that before the series ended. 'So, what do you do if you've had that kind of success that you've never expected?  Well you can go one of two ways. 'You can think: "Oh no how dreadful, I'll never, ever top that", or you say say: "How incredibly marvellous and liberating, you know, that I made money beyond my wildest dreams, I can affect issues that I really care about. '"But what do I love doing?  I love writing, so clearly I'm going to continue to write." 'But I don't know.  I absolutely don't sit around and think I must now write a THIS kind of novel to prove that I can write it, because I always did write what I wanted to write and I will continue to do that.' The author, who has said she was 'as poor as it's possible to be' when she wrote the first Harry Potter novel as a single mother who would have just one Rich Tea biscuit for dinner, has made an estimated £1billion fortune from her books, which were also turned into films. Philanthropy: The author was publicising her Lumos charity, set up to fight children being institutionalised . The first Harry Potter was made into a film in 2001 starring Rupert Grint, Daniel Radcliffe and Emma Watson . Family: JK Rowling, 48, lives in Edinburgh with her doctor husband, Neil Murray - they married in 2001 . She published her most recent work, crime novel The Cuckoo Calling, in April this year under the pseudonym Robert Galbraith.  After Rowling was revealed as the true author, sales rose by 4,000 per cent. Rowling's revelations came during an interview to publicise her charity Lumos, which she set up eight years ago to fight the institutionalisation of children. The author, who is said to have given millions to charity, said: 'There are 8m children globally being raised by institutions and everything we know about institutionalisation tells us it's harmful to children's physical and mental health. 'To take a child from their family...it's about the worst thing you can do to a child... That's what we're working to end.'
multi-millionaire. Author JK Rowling, 48, said books had brought her 'money beyond my wildest dreams', which was 'marvellous and liberating'. book, Harry Potter and the Philosopher's Stone, £1billion, says she knew in 2000 she would never Watson . Family: JK Rowling, 48, lives in publicise her charity Lumos, which she set up of children. The author, who is said to have