The BBC is running a three-part interview with Miriam Marx entitled "Groucho Was My Father." You should be able to listen to Part One at this link. If it doesn't work, try looking around on this page for a link that will play through your browser.
Part Two airs this Sunday and shortly after it does, Part One may disappear from the website and be replaced by Part Two. I'll link to Part Two once I know it's up but in the meantime, you might want to listen to Part One before it goes away. And yes, that's our pal Frank Ferrante doing the Groucho impression. Who better?