Plaque: Terence MacSwiney
Terence MacSwiney, 1879 - 1920, Lord Mayor & MP, died on hunger strike in HMP Brixton after 74 days. 25-10-1920.
According to Wikipedia MacSwiney "was summarily tried by a court on 16 August and sentenced to two years' imprisonment at Brixton Prison in England. In prison he immediately started a hunger strike in protest at his internment and the fact that he was tried by a military court." So the earliest the hunger strike could have started was 16 August, which is 70 days before his death, not 74. He had been arrested on 12 August which would give 74 days, if he had started the fast on arrest rather than imprisonment.
Site: Terence MacSwiney (1 memorial)
SW2, Lyham Road, Rear wall of Brixton Prison
Google Street View shows that this 'plaque' was painted on the wall between May 2012 and September 2014.