The earl petitioned the king that the class of occupants they both hoped to attract to the new district would not take houses without the prospect of eventually acquiring them outright, and in 1665 the king granted the freehold of the site of St. James's Square and some closely adjacent parts of the field to the earl's trustees.

The houses on the east, north and west sides of the square were soon developed, each of them being constructed separately as was usual at that time.

The windows were more widely spaced than most, the ceilings were high, and deep plots and ingenious planning allowed some of the houses to contain a very large amount of accommodation indeed (see the plans in the Survey of London extract linked below and note that this is not reflected in the extract from Horwood's map shown as he had no access to the interiors).

Some of the houses had fine interiors by leading architects such as Matthew Brettingham, Robert Adam and John Soane.

The idea of buying them out, demolishing their houses and leaving the space open to the Pall Mall was raised more than once, but never implemented.

Although the plans for the fountain were later abandoned, and water no longer supplied by the 1730s, the basin remained until 1854, when it was removed following complaints by residents during a cholera epidemic.

[3][4] Things began to change by the 1830s with the arrival of club-houses, and in 1844 The Builder commented that the square was losing caste and the fashionable were migrating to Belgravia.

By 1857 the square contained a bank, an insurance society, two government offices, the London Library, two lodging-houses and three clubs.