The Radcliffes in the IOM were confined to three or four parishes until the mid to late 1800's. It is probably unsafe to generalise that surnames are restricted to specific parishes until you have done a good few years of research on them.

There are four Catherine Radcliffes christened in Andreas around 1835, but only one shows up in the 1851 census.

The most likely is the daughter of Thomas R and Leonora Corlett ch 25 Aug 1833. Others parents are John and Elizabeth Crennell ch 7 Jan 1834, John and Mary Teare ch 15 Nov 1834, and Thomas and Catherine Clague 14 June 1834.

Next step would be to try and tie them down through wills. Thomas husband of Leonora died in 1874 (from MI) but the Thomas 1874 will on Brian Lawsons site is probably not the same Thomas.

Regards, Ian