[8] Billing began his career with a curacy at St Peter's, Colchester between 1857 and 1860, and then in Compton Bishop, Somerset from 1861[9] This was followed by a period as Secretary of the Church Missionary Society.

In 1863 he became Vicar at Holy Trinity in Louth[10] the living consisting of a vicarage endowed by the Ecclesiastical Commissioners with £300 a year (in 1872), in the gift of the Bishop of Lincoln.

He was then promoted to Rural Dean of Spitalfields in 1878[11] and 7 July 1888 The Morning Post announced in their Whitehall notices that: "The Queen has been pleased to direct letters patent to be passed under the Great Seal of the United Kingdom of Great Britain and Ireland for presenting Doctor Robert Claudius Billing to the Rectory of St Andrew Undershaft with St Mary-at-Axe, in the city and diocese of London, void by the appointment of Doctor William Walsham How to the Bishopric of Wakefield.

He took a long period of rest but was compelled in 1895 to resign his bishopric while retaining his old position of Rector of St. Andrew Undershaft in the city in the east end of London few men were better known or more highly popular.

The Times reported, "Bishop Billing had been an invalid for several years past, an affection of the brain having disabled him from transacting even work of a routine character.

Strong in experience, common-sense, zeal, faith, humour, hopefulness and sympathy, whether as guardian of the poor or in the organisation of charity for the care of souls, in reclaiming the fallen in rescuing children, in the elevation of the people or as friend and Father of his clergy.