The main organ was built in 1867, slightly altered in 1892 and again rebuilt in 1983 by the same leading English firm of J W Walker and Sons now based in Suffolk. When first installed there were insufficient funds for the pipe work for the third manual, and similarly in 1983 no third manual was installed. However in 1983,as well as useful improvements being made, the manual nearest the player was made a coupler manual combining the sound from the swell and great manuals. The result is that what appears to be a three-manual organ is a two-manual organ with a manual coupler. It is fortunate that standing at the far end of the north aisle, a favourite position at the time, the pipes have a good space in which to speak. It is a comfortable instrument to play. There are other larger and "better" organs even in the near-vicinity. However they may have disadvantages; one with many really beautiful stops is difficult for the player who is not well sited to hear the effects; another is in a church with a really wide chancel.
A beautifully varied casson positive organ - again with plenty of spotted metal - can be found in the Lady Chapel. We are fortunate indeed and were surprised when the Organ Club included Holy Trinity in its tour of South Suffolk in April 2000.