Gray was active both in municipal and national government for much of his life, and had nationalist ideals[2] – which he expressed as owner of the Freeman's Journal, chairman of the Dublin Corporation Water Works Committee between 1863 and 1875, and Member of Parliament in the House of Commons of the United Kingdom of Great Britain and Ireland for Kilkenny city from 1865 until his death.

Shortly after his death, his contributions to the provision of the water supply, and the beneficial impact this had to conditions of public health in Dublin,[5] were recognised in a memorial statue on O'Connell Street.

[9] The trial had a strong element of farce, as the hot-tempered Attorney General for Ireland, Sir Thomas Cusack-Smith, challenged Gray's counsel, Gerald Fitzgibbon to a duel, for which he was sternly reprimanded by the judges.

From then on Gray was careful to distance himself from the advocacy of violence in the national cause, though he was sympathetic to the Young Ireland movement without being involved in its 1848 rebellion.

[8] Later Gray was to originate and organise the "courts of arbitration" which O'Connell endeavoured to substitute for the existing legal tribunals of the country.

[2] Partially in recognition of these efforts, Gray would later be nominated for the position of Lord Mayor of Dublin for the years 1868–69, but he declined to serve.

In an unusual alliance with the Catholic Archbishop of Dublin, Paul Cullen (1803–1878), a man devoted to O'Connell's memory, Gray's newspaper exploited this shift in government policy.

He fought for the provision in the new Landlord & Tenant (Ireland) Act 1870 for fixity of tenure, which Gladstone eventually conceded.

The monument was completed in 1879 and was dedicated to the "appreciation of his many services to his country, and of the splendid supply of pure water which he secured for Dublin".

[11] His legacy also included his contributions to the passage of the Irish Church and Land Bills, his advocacy for tenant's rights[7] and his support of the Home Rule movement.