Dr Parker was twice chairman of the London Congregational Board and twice of the Congregational Union of England and Wales. In 1887 he visited the United States, where he delivered a eulogy on Henry Ward Beecher, with whom he had been on very intimate terms. On 22 December 1864, Parker married Emma Jane, daughter of Andrew Common JP, banker, of Sunderland. Her death, on 26 January 1899, was a blow from which he never fully recovered. She was buried at the West Hampstead Cemetery.