Macklin is perhaps best known for the South African War Memorial, previously known as the Northumberland War Memorial (sculpted in 1907; unveiled in 1908) in Percy Street, Newcastle, which is Grade II* listed. He and Charles Septimus Errington (1869–1935) were first asked to submit plans for the monument in 1904, and in 1905 it was announced that Macklin had won the competition to execute the work. Macklin's wife Alys was the model for two of the figures on the top and at the base of the monument: Peace and Victory. Standing 24m tall, it is the oldest and largest war memorial in the city, memorialising "373 officers and men of Northumbrian regiments who fell in the South African War". It was unveiled by Lieutenant-general Sir Laurence Oliphant on 22 June 1908, in front of a crowd of about 30,000. Afterwards, the chairman of the Executive Committee, Sir Henry Scott, spoke of "the success of [Macklin's] efforts and the artistic beauty of the result". By 2016, it had become known as the "Dirty Angel" or the "Mucky Angel", and Newcastle City Council had granted planning permission to repair and refurbish the memorial.
