Regency Square was developed by Joshua Flesher Hanson between 1818 and 1828, he was in possession of the site (probably by purchase from Kemp) by 1818. He fenced off the central area and divided the perimeter into 70 plots, letting them to various builders on building leases containing an option to purchase. It is clear that Hanson intended a development of good quality and consistent style. A printed memorandum of agreement with a builder named Saunders for a plot on the east side of the square stored with the deeds was presumably a standard document for all lessees. It had very specific conditions:
Hanson was himself responsible for setting out the enclosure: he agreed that within one year of the date of the memorandum he would enclose the lawn within a single iron fence 'with gates and lamp irons'. The railings were similar in design to those found in front of the square's houses today. Historically the square is of particular interest as one of the first in Brighton, and therefore one of the first in the country, to have gas lighting. In 1827 the lamps were described as rivalling daylight in their brightness. There were 21 lamp posts of quite elaborate design set within the railings, including two either side of the gates at the north and south entrances.
By the 1850's the enclosure had a layout of shrubs, path and central lawn. In the late nineteenth century the shrubs were replaced by a formal hedge and there was a small amount of planting within the Lawn. As the gas lamps were superseded, they were replaced by large metal spikes.
The owners of the 'privileged houses' (all of those in the square except numbers 44-50) were to pay for keys to the gate, and the lawn was to be used in perpetuity as a pleasure ground. Other documents make it clear that the facades of yellow brick above balcony level were to remain unrendered. This is still the case for a few properties and as late as the 1940s many facades were still exposed brick.
Most of the square was completed by 1828, but St. Albans House (1 Regency Square and 131 King's Road, originally known as Regency House) was not completed until 1830 and is known to have been designed by Amon Henry Wilds. Dale considers that, on stylistic grounds, 47-50 were probably built last of all. St Albans house was occupied between 1830 and 1837 by the Duke and Duchess of St. Albans and number 2 was occupied between 1828 and 1830 by Dr William King, social reformer and cooperative pioneer.
The relatively minor changes to the enclosure in the late nineteenth century reflect what was, in the event, a smooth transition from private to public ownership of the land. Hanson set up the covenants with the privileged houses for a period of 71 years rather than in perpetuity, and the earliest of the covenants dated from 1818. As the time of expiry approached, some residents, led by a prominent local solicitor, Somers Clarke, were sufficiently alarmed to seek a private act of Parliament to continue the covenant. Their attempt was unsuccessful, but Somers Clarke persuaded the Brighton Corporation to compulsory purchase the enclosures using its powers under the Brighton Improvement Act, 1884. The last survivor of Hanson's trustees, John Austin was given £50 in compensation and all of the covenants were perpetuated indefinitely. Somers Clarke maintained a close watch on standards in the square into the twentieth century: for instance, in 1902 he was complaining to the Town Clerk that some houses had been incorrectly painted.
The Boer War Memorial was unveiled in October 1904 and subsequently became the Royal Sussex Regiment's memorial for both World Wars. It was designed by John William Simpson, who was also responsible for Roedean School, a couple of miles along the coast to the east. He also designed, either individually or with others, City Hospital, Liverpool, Victoria Institute, Worcester, Manchester Royal Infirmary, Glasgow's Kelvingrove Art Gallery and Museum, Cartwright Memorial Hall, Bradford and with Maxwell Ayrton was responsible for Wembley Stadium.
At some time after World War I, the Regency Square enclosure lost its exclusivity. Perhaps this was associated with the conversion of properties in the square to hotels. By the early 1930s the enclosure had up to six lawn tennis courts set out and prominent safety netting had been set up around the edges. An entrance kiosk appears to have been set up near the south gates.
The exact sequence of events within and around the enclosure during World War II is not known, but the result is evident from the picture below. By the end of the war, all of the railings and lamp standards and stone plinths had been removed. Air raid shelters had been excavated and the area appears to have been used for storage. Only a ragged hedge survived from the pre-war landscape.
The square was levelled and put down to grass soon after the war finished and the most of the lighting columns to be seen today probably date from the 1960's. There appears to have been little further change around the square until the early 1960's when Abbot's Hotel in the south east corner was demolished and replaced by the present block of flats. During the 1960s, conversion of the former enclosure site to a car park was discussed and it was eventually decided to place the car park underground. Steps were built around the war memorial to give pedestrian access to the centre of the square, entrances to the car park were placed at the north and south ends and large grilles were placed across the centre of the square from east to west.
To the south of the square, the appearance of the West Pier deteriorated after the war. It closed to the public in 1975 and the western toll booth was demolished, significantly affecting the view from the square. On a more positive note, the facades of several buildings in the square have been improved in recent years through grant aid schemes.