Emo Court is the product of several architects, of whom James Gandon was the first and the most famous. He designed the front facade of the house around 1790, and provided designs for other parts which were not fulfilled. Work on the house came to a halt with the death of the 1st Earl of Portarlington in 1798. Gandon was succeeded by Louis Vulliamy, a British architect who was assisted by the Irish Williamson brothers and who was employed by the 2nd Earl.
Matthew, John and Arthur Williamson were builders, property developers and architects with a practice in Dublin. All three of them were active in the first quarter of the 19th century, mainly in Rathmines and Monkstown, but generally very little is known of their careers. Matthew Williamson died c1827, John possibly in 1838, and Arthur in 1846.
The first - and only - known drawing attributed to Matthew is a proposed design "A Section of the Salloon [rotunda] at Emo Park" which is inscribed 'by M Williamson 1812' and can be viewed in the Irish Architectural Archive.
Also in the Archive, there are signed and dated drawings by A and J Williamson for various works at Emo Court between 1822 and 1831: north and south porticos, north front, drawing room ceiling , out-offices, ice-house , and sluice.
John Williamson also proposed designs for the Wellington Monument in the Phoenix Park in Dublin, presumably an entry for the competition held in 1814-15.