Edward Cephas John Stevens was born on 18 October 1837, at Salford, Oxfordshire, England, the youngest son of the local rector, the Reverend William Everest Stevens, and his wife, Mary James. He was educated at Marlborough College and at the Royal Agricultural College, Cirencester. Stevens chose to emigrate to Canterbury, New Zealand, arriving at Lyttelton by the Zealandia on 20 September 1858. Among the passengers were John Henry Whitcombe, surveyor, his wife, Maria Whitcombe (formerly North), and their family. Maria Whitcombe was widowed in 1863, and she and Stevens were married on 20 May 1869 at St Peter's Church, Riccarton. They had two sons, one of whom died in infancy.
Stevens spent two years or more on Banks Peninsula, and on returning to Christchurch took up the business of land agent and representative of absentee landholders in 1861. In April 1862, with Richard Harman, a well established colonist, he founded the business of Harman and Stevens, land and commission agents, a firm which operated successfully for over 50 years.
Through Harman, a founder of the Christchurch Press, Stevens was soon closely involved in that newspaper's finances. Before long they became the financial managers in order to protect the substantial debt owed by James Edward FitzGerald. It was in this connection that Stevens confronted FitzGerald, gradually imposing a regime which led the latter to describe Stevens as a 'thorough Jew'. A foreclosure on FitzGerald's property at Lincoln by Stevens did nothing to ease the relationship. Both Harman and Stevens maintained an active, though not lucrative, link with the Press for over 50 years, with Stevens eventually becoming chairman of the board.
Stevens quickly became identified with numerous public activities, of which cricket was pre-eminent. He may be ranked after W. G. Brittan as the founder of Canterbury cricket. He played for the Canterbury Twenty-two against the visiting English cricket Eleven in February 1864, and he was one of the few responsible for raising the finance which made the visit possible. He played for Canterbury against a second visiting English side in 1878, winning a bat for the best Canterbury batting. Stevens was a regular player for Canterbury until 1883, and continued to play the game into the next century. He and A. M. Ollivier initiated the acquisition, in 1882, of the ground which became Lancaster Park. Stevens acted for his firm in selling the land on behalf of an absentee owner, Benjamin Lancaster.
Stevens was as much addicted to politics as he was to cricket. He was a member of Henry John Tancred's provincial executive between 1863 and 1866. He strongly disapproved of Samuel Bealey's superintendency, and left provincial politics when William Sefton Moorhouse came back into power. In that same year, 1866, he entered Parliament, obtaining the uncontested Selwyn seat. He established himself as a speaker of capacity, especially in matters of public finance, expressing his views with confidence, and, it is said, in an oracular style. He does not seem to have had close links in the House with other Canterbury members save in 1869 in the temporary grouping known as the 'Stand Aloof Party', which included Henry John Tancred and William Rolleston; they hoped to hold a balance between Edward Stafford and William Fox. In the eyes of Stafford, the group were the 'Impracticables'.
In July 1869 Stevens advanced a series of eight proposals for constitutional reform. Far-reaching in intention, they called for the abolition of the provincial system of government, the reform of taxation measures, the consolidation of all provincial loans with those of the colony in order to protect colonial credit, and as a matter of immediate concern, the formulation of a scheme to revive colonisation. A long debate ensued before the motion to defer the proposals to the next parliament was carried by 33 votes to 22. Within a year of Stevens's resolutions, William Fox and Julius Vogel were to advance their own scheme for reviving colonisation, which contained the seed for the abolition of the provinces. Stevens lost his Selwyn seat to William Reeves by one vote, and for four crucial years could not participate in the debates on Vogel's measures. He won the City of Christchurch seat in December 1875, still loud in his criticism of the provincial system.
Stevens retained his seat in 1879, and was involved again in attempts to form a middle party in 1881. In that year he retired from the House, where for some years he had served as chairman of the Public Accounts Committee. He entered the Legislative Council in 1882. In 1887 he declined Harry Atkinson's offer of the colonial secretaryship but accepted a position on the Executive Council until Atkinson's defeat in 1891. Thereafter he was a discerning critic of bills from the House, especially those concerning land. Although always opposed to the compulsory acquisition of land by the Crown, once the Liberal policy had been endorsed by the electorate in 1893 he agreed that it should be accepted. He remained a member of the Council until 1915.
Through Stevens's advocacy, Vogel was led to introduce the bill which created the Public Trust Office in 1872. At the time of Stevens's death it was stated that the success of this scheme gave him particular satisfaction. A commemorative tablet acknowledging his work was placed in the Public Trust head office.
Among many other public activities, Stevens was a member of the North Canterbury Board of Education in 1878, and of the Canterbury College board of governors from 1875 until 1899 with a break of one year. When the board of Canterbury Agricultural College was set up in 1896, he became a member and was chairman from 1897 until the year of his death. He was chairman of the Horticultural Society for some time, flower cultivation being one of his interests. His special knowledge of finance led to his helping form the Permanent Investment and Loan Association of Canterbury in 1871, of which he was for a period manager and director. The Christchurch Club, an exclusive body from the early years of the settlement, also attracted his notice. He was president from 1877 to 1910 and piloted the club through the difficult years of the 1880s and 1890s.
Stevens also served as secretary of the Canterbury Boating Club. In 1862 he bought for £3,000 the substantial house Englefield, which still stands; it had a commanding view of the annual opening of the boating season.
In 1910 Stevens was described as 'an extraordinary old man, with dirty boots and a shrunken pair of trousers, wearing over his shirt a long raw-silk dust coat and a sailor hat. He mumbled his speech through a grey moustache overhanging his beard'. Suffering from heart failure, Stevens died in his sleep on 6 June 1915. He left a substantial estate of £282,272, which was divided among his wife, his son Charles, and members of the Whitcombe family.