 He succeeded Timothy Healy as Parnell's private secretary in 1880 and in the 1885 general election was elected for the new parliamentary seat of South Fermanagh by 3,574 votes to the Conservative's 2,181.In the 1886 general election he was re-elected against the same opponent by only a slightly smaller majority.He was a key witness in Parnell's defence before the Parnell Commission of the late 1880s and indeed for the most part it was Campbell's writing rather than Parnell's which had been forged by Richard Pigott in the plot to discredit Parnell.