Today most children in Finland learn English early on at school, but that certainly wasn't the case for someone born in 1935. I'm just guessing, but she's probably picked up the language later in life. Also, a Finn of her generation didn't hear English on TV all the time and didn't play video games as a kid :)

As a side note, I know a lot of people that are excellent at English but have an accent. I don't think all people make it a priority to get rid of their accent (or to gain an accent), especially if they don't live in an English speaking country.