 She became the Deputy Chief Constable of Sussex where Wallis was awarded the Queen's Police Medal(QPM) in January 2002.At the time Wallis was short-listed to head the Police Service of Northern Ireland (PSNI) in her native Northern Ireland, but withdrew following her promotion to Devon & Cornwall.As Chief Constable of the Devon and Cornwall Constabulary, Wallis presided over the fourth largest reduction in crime out of all the police force areas of the UK in 2005–2006.