[1] After taking his degree in 1880, Parker entered at Lincoln's Inn as a student and read in the chambers of Matthew Ingle Joyce.

Assigned to the Chancery Division, he rapidly acquired a judicial reputation, and sometimes sat as an additional judge of the Court of Appeal.

At the outbreak of the First World War, Parker lobbied privately ministers to introduce price controls, without success.

In 1915, he spoke to the House of Lords about post-war reconstruction, and during the passage of the Representation of the People Act 1918 Parker (who had deputy high steward of the University of Cambridge since 1915) successfully pressed the Lords to allow women to vote in university constituencies even though they were disbarred from taking their degrees.

[1] On 19 March 1918, shortly before his death, Parker spoke on a motion by Lord Parmoor in favour of a League of Nations.

[1] His health failing, Parker carried on working until the summer of 1918, before he died on 12 July at Aldworth House, near Lurgashall, Sussex, the former residence of Lord Tennyson.