Roberts was a Londoner, a pupil of Charles Fowler, and who in 1825 became an assistant to the renowned Sir Robert Smirke with whom he stayed for four years, but he had built nothing of importance by himself. Smirke had a reputation for sound construction using concrete foundations, and he repaired Laing’s ill-fated Custom House after its collapse.

The old livery hall of the Fishmonger’s Company, which was built after the Great Fire, had to be demolished to make way for the new approaches to London Bridge and, in September 1831, one month after the new bridge had been opened, the City of London Corporation announced that an architectural competition would be held for the design of the new hall. The first prize was awarded, in March 1832, to the twenty-nine year-old Henry Roberts. Much of the detail of Roberts’ Fishmonger’s Hall resembles Smirke’s classical detailing, particularly the use of Smirke’s favourite Ionic order. Soon after the announcement of his success in March 1832, Roberts single-handedly set to work to produce all the detailed constructional drawings required to enable the builders to tender precisely for the cost of the building. This mode of procedure, which was comparatively new at the time, had great advantages for the prospective building owner compared to the old system where individual tradesmen quoted only for their part of the work and overall co-ordination, as such, was in the hands of a Clerk of Works.

The new system not only let the owner know exactly how much the final expenditure would be, but by inviting tenders from various builders, he could be sure that he was getting it at the lowest cost, and by inserting a completion date in the contract, he knew when he could get his building. This arrangement was only made possible by the emergence of the large general contractors, such as Grissell and Peto, who were capable of producing every part of a building, from brickwork to joinery. But it did give the architect the task of producing all the drawings and specifications for the entire project, before tenders could be invited. But by May Roberts was reported as being ill ‘from the effects of over exertion in preparing the Drawings’, so it must have been soon after that he invited Sir George Gilbert Scott to join him at his office in Suffolk Street, just off the Haymarket.

The young Scott’s detailed examination of his drawings and specifications must have impressed Fowler, who probably recommended him to Roberts for the work as Roberts had been his pupil. Sir George Gilbert Scott was Robert’s only clerk and stayed with him for two years.