The main change in defining the rights of Trinity House occurred 1786, when the Parliament of George III passed an Act which clearly defined the powers of the Corporation, as well as creating the Corporations of the Commissioners of Irish Lights and the Commissioners for the Scottish Lights [George,,26/38]. Scotland and the Isle of Man were to be covered by the Commissioners of the Northern lights; Ireland would be managed by the Commissioners for Irish Lights and England and Wales would remain with the Corporation of Trinity House.
In principle, the Act seemed workable and for 50 years most activities covered by the three Corporations ran smoothly. Only one major item had to be addressed - the problem of private lighthouse owners. Concern was voiced in Parliament over their reluctance to spend money on necessary repairs and upgrading of their lights. An 1836 Act of Parliament enabled compulsory purchase orders for all private lighthouses. All previous patents were surrendered to the relative Corporations with compensation paid by the Treasury. In reality, the major part of the funding came from the Corporations and the so-called money from the Treasury turned out to be a State loan.
In 1850, the Government had recovered its loans but there was still concern over the powers of the Corporations, so, in 1854, the Government amended the George III Act and transferred many of the responsibilities to the Board of Trade.
For Ireland, the Merchant Shipping Act of 1854 conferred to the port authorities the new title of 'The Port of Dublin Corporation'. This Act effectively divided the existing Authority in two, with identical constitution and personnel, but separate functions. When the division of the authority was completed in 1867, the Port of Dublin Corporation became the Commissioners of Irish Lights. The other group became the Dublin Port and Docks Board. However, archive records for the lights of Ireland show that 'Trinity House of Deptford Stronde' still had a considerable influence over the matters relating to Irish lighthouses. Although most of the Parliamentary reports show Trinity House in an 'advisory capacity', it was still using its power of the 1685 charter which demanded that the erection of any lights around the British Isles must first be sanctioned by its Elder Brethren.
The original constitution of the Commissioners was a Board of twenty-two, including the Lord Mayor and the High Sheriff of Dublin, three Alderman elected by the Municipal Corporation of Dublin each year and seventeen co-opted Members filled by the Board when vacancies occurred. Today, the High Sheriff of Dublin has been abolished and the number of Commissioners is twenty one. These Commissioners maintain in Irish waters all aids to navigation which are of benefit to shipping. The Local Authorities and Harbour Boards maintain all the local aids, but they are required to seek the statutory sanction of the commissioners of Irish Lights under the Merchant Shipping Act of 1894, for any alterations or additions they wish to make to their navigational aids.
A report dated 1861 and provided by a Royal Commission clearly pointed out the confused organisation and needless expense that had occurred since the involvement of the Board of Trade. For the 402 lighthouses and other lights around the British Isles, it now needed 174 different local authorities to administer them [Findlay, 1862].