Patterson defected to the Democratic Unionist Party (DUP) in June 2016, a month after losing his seat in that year's Assembly election.

[1] As a member of the Ulster Unionist Party, Patterson was co-opted to the Northern Ireland Assembly in January 2016, having replaced Neil Somerville, following the latter's resignation due to ill health.

Patterson contested the 2016 Assembly election, alongside his running mate, Rosemary Barton.

Following his defeat, he went on to defect to the Democratic Unionist Party, saying he was "let down and disappointed" by UUP decisions both locally and nationally.

In an email to Ulster Unionist members, Patterson revealed that the majority of his friends and families were DUP supporters and that he "at a time of weakness on my part give [sic] into the advice they have been giving me since the Election"[3] Outside politics, Patterson spent over twenty years in the Construction Industry, most recently serving as a Senior Quantity Surveyor.