From 1958 to 1968, Marsden was a cast member of the radio series Beyond Our Ken and Round the Horne, where she played most of the female characters. Perhaps her most famous catchphrase was "many, many, many times", delivered in the dry, reedy tones of Bea Clissold, the ancient actress who was renowned for having given pleasure to many, particularly in "The Little Hut" on Shaftesbury Avenue. This long outlasted the Clissold character and was deployed to much audience appreciation on a few occasions in later series, possibly as an ad lib. Another was " 'allo, cheeky face!", shouted into the microphone in the less-than-couth London tones of Buttercup Gruntfuttock. Marsden's vocal range was impressive and also included the husky Daphne Whitethigh, the strident stereotypical Aussie tones of the ultra feminist (but conflicted) Judy Coolibar, and the cut-glass Received Pronunciation of Dame Celia Molestrangler (in a series of loose pastiches of the stilted dialogue in 1930s and 1940s romances and melodramas – for example, The Astonished Heart became The Hasty Nose, and Brief Encounter became Brief Ecstasy – partnered with Hugh Paddick's 'ageing juvenile Binkie Huckaback', with the denouement inevitably bringing the lovers crashing back to earth).
During the Second World War, Marsden met and married Dr Jimmy Wilson Muggoch, an army doctor from Edinburgh.[7] From 1963 the couple lived in Brentford on their houseboat Chilham, a converted Thames lighter.[8]
Prior to her death, Marsden had been suffering from heart problems and pneumonia. She was believed to be recovering, but died suddenly while socialising with friends in the bar of Denville Hall, a retirement home for actors, in Northwood in London.[7]
