He established a photography business in Peckham in 1862 using William Fox Talbot’s Calotype negative/positive printing process.
In 1879 Harman abandoned his photographic studio and moved to Ilford village where he began manufacturing dry gelatine plates in the basement of his new home in Cranbrook Road on the corner with Park Avenue.
His early processes were rudimentary—he applied his emulsion formula with a teapot—but the huge growth in the photography market gave him the revenue he needed to build purpose-built premises in 1883.
However, the directors of the much smaller Ilford perceived it as a takeover attempt, and Harman was persuaded to reject the proposal.
In 1900 he offered to finance a church in Grayswood, on land given by Lord Derby, on the condition that a parish be created there.