Cockerell received his training in the office of Sir Robert Taylor, to whom he allowed that he was indebted for his early advancements, which were largely in the sphere of official architecture.

In 1774 he received his first such appointment, as Surveyor to the fashionable West End London parish of St George's Hanover Square.

[6] At the death of Taylor in 1788, Cockerell succeeded Sir Robert as Surveyor to the Foundling Hospital and Pulteney estates.

In 1790 he presented the board of governors of the Foundling Hospital a project for the development of their considerable estate in Bloomsbury, London, which proceeded according to his plans, until he resigned and was succeeded in the post by his pupil Joseph Kay.

[8] Cockerell designed the architecture of much of the Bayswater area of London, including Sussex Gardens, but in other urban planning schemes he was less successful.

[10] Another abortive development about the same time was for a "Carmarthen Square" on the Mortimer estate in Bloomsbury; eventually the land was purchased for the University of London.

He had built an entrance and bridge at Whiteknights, near Reading, in Berkshire, for William Byam Martin, an acquaintance of Hastings'.

[16] In the severely undecorated elevations finished in warm golden Stanway limestone, windows are simply pierced in the ashlar masonry without even moulded surrounds.