 Most of the 1899 pipe-work was re-incorporated to provide a summary of 29 speaking stops, 2 tremulants and 19 couplers, with a new electro-pneumatic action and the original four-manual console (keyboards) as before.During 1956–57, the organ was completely reworked, with a number of tonal additions, and rebuilt by J. W. Walker & Sons Ltd.The Great, Swell, Solo and Pedal were moved to the North Transept Gallery and provided with new case work designed by Messrs Ian G. Lindsay & Partners, Architects of Edinburgh.