He spent a brief period in a dame school but had no other formal education and began work in a shoemaker's shop aged ten.
Applegarth campaigned for the pro-trade unionist minority report of the commission to be accepted by Gladstone's Liberal government, leading to the Trade Union Act of 1871.
At around this time he joined the Working Men's Committee for Promoting the Separation of Church and State along with Potter and George Howell.
After his work for the Royal Commission, Applegarth became a commercial traveller for a French firm selling Henry Fleuss's underwater breathing apparatus.
When his old friend Howell lost his seat in Parliament in 1895 and fell ill, Applegarth and the TUC raised a £1650 testimonial to buy him an annuity.