The local sporting ambassador was tragically killed during a practice session at the Skerries 100 in County Dublin on Saturday.
The Mayor, Councillor Brenda Chivers has expressed her deepest sympathies saying: “The entire Borough has been left shocked and saddened with the tragic events that unfolded at the weekend.
“I wish to extend my deepest sympathies to the entire Dunlop family at this very sad time.
“William was a fantastic sporting legend and he will be remembered for his many achievements.”
Books of Condolence are available for members of the public to sign at Ballymoney Town Hall, Coleraine Town Hall, Roe Valley Arts and Cultural Centre, Limavady and Sheskburn House, Ballycastle from noon on Monday.
The Roe Valley Arts and Cultural Centre and Sheskburn House will both be closed on Thursday 12th and Friday 13th July due to the Bank Holiday. Ballymoney Town Hall and Coleraine Town Hall will both be open as normal.
The books will close at 5pm on Friday 20th July.