Born in Belfast, Lewsley attended the University of Ulster before working as a cook and an advice worker. She is married with five children and six grandchildren.
In 2001, she was elected to Lisburn City Council. She was a co-founder of Shopmobility in Belfast and initiated the appointment of the only Disability/Equal Opportunity Officer in local government.
On 19 December 2006, Lewsley resigned from the Assembly in order to take up a post as Northern Ireland Commissioner for Children and Young People,[1] and took up that post on 8 January 2007. She served two four-year terms as Commissioner and her final term came to an end in January 2015.[2]