 Aged 23, he joined Perry & Company, a civil engineering contractor founded by East End carpenter John Perry, based in Bow, east London, in 1865.He became a partner in the business in 1872, and after the death of Perry’s three sons, became sole proprietor in 1888.In 1897, Bartlett signed a £877,000 contract to construct a deep tube under the Thames from Waterloo to Baker Street - part of the present-day Bakerloo Line.