"That on the application of the owners, the Martin Estates Ltd., a new street on their property, situate off Cadogan Street and Curzon Street, be named Pitman Street". (30th April 1907).
Probably belongs to a cluster of streets named after Royal Navy admirals—Cadogan Street, Curzon Street and Penrose Street—in which case it commemorates Vice-Admiral Cuthbert Collingwood, 1st Baron Collingwood (1748-1810), second-in-command at Trafalgar and Commander-in-Chief of the Mediterranean Fleet after Nelson's death. Given that these four names form a tight themed cluster, Collingwood Avenue is almost certainly named after Vice-Admiral Collingwood.
Application of the owners the Martin Estates Company Ltd two new streets on their property off Donegall Road be named Kitchener Street and Soudan Street and three new streets off their property situate off Agincourt Avenue - Collingwood Avenue, Cadogan Street and Curzon Street. Minutes, TIC, 12th October 1898.
"That on the application of the owners, the Martin Estates Ltd., a new street on their property, situate off Cadogan Street and Curzon Street, be named Pitman Street". (30th April 1907).
"That on the application of Messrs. The Martin Estates Co. Ltd., the name of a street on their property situate off Agincourt Avenue be changed from Pitman Street to Collingwood Road". (9th February 1909.).
"Proposed Continuation of Existing Street Collingwood Avenue, BT7 1QT Between Carmel Street and Damascus Street, BT7". People and Communities Committee 13th June 2023.