Grainne grew up in London, and has a convergence of British, Irish, Jewish and Anglo-Indian heritage. Prior to training at The Oxford School of drama she trained at the National Youth theatre. She has also performed at the ADC, the Cambridge Arts Theatre and her company Three Sisters Productions, has taken plays to the Edinburgh Fringe, Theatre503, The Northwall and The Bunker. One of them is now in development to be a series. She has worked as a translator for a classical theatre company in Spain, and speaks fluent Spanish. Grainne is also a keen writer.