In 1856 the comment was made ‘It is quite unsafe for a respectable person to walk at night in the New Dock area, so unruly are the men and women who frequent the public houses there.’ Throughout 1856, 1857 and 1858 members of Capel Newydd, Mount Pleasant, raised money to enable a place of worship to be built near the South Wales Railway Station.

Trinity was proud to celebrate its centenary year in 1958 and when Siloh, Lakefield Road, was forced to close its doors the members transferred to Trinity.

A William Isaac clock once adorned one of the walls of the Sunday School. William Isaac, Watchmaker, was listed in Trade directories from 1835 to 1872. The clock with the wording "WM ISAAC LLANELLY," is still working and is said to be about 150 years old.