In 1852 Evans was appointed a clerk in the chancery pay office, a post he held until 1882, when his health enforced his retirement.
In 1858 he began to collect fossils from the tertiary formations of the south of England, and formed during the next twenty-five years very complete sets illustrating the strata of the London district.
In 1857 Evans took part in founding the Geologists' Association of London, of which he was for many years one of the most active members, and in 1867 he was elected a fellow of the Geological Society.
He was fortunate in being able to take advantage of the operations in connection with the main drainage works in the south of London, which afforded opportunities for collecting fossils never likely to recur.
He made large collections of its fossils, and his paper 'On some Sections of Chalk between Croydon and Oxted,’ read to the Geologists' Association in January 1870, marks the first English attempt to divide this immensely thick mass of pure white limestone into several zones, and to correlate these zones with those that continental geologists had already established.