Scott's designs for the reconstruction of St. John's Cathedral, Newfoundland, were made at the same time as Ramsgate. In 1846, a great fire swept through the little city of St. John's destroying most of the buildings, including the wooden Anglican cathedral. The Right Reverend Edward Feild (1801-76), had been a lecturer at Oxford and had only gone out to St. John's as Bishop two years previously. He thereupon returned to Britain in the autumn of 1846, to obtain designs for a new cathedral and, perhaps through his Oxford connections, asked Scott to produce a design. This was the first of six new cathedrals that Scott was to design and, as such, it should have been another boost to his status as an architect. However, in reality, St. John's was then a small bleak settlement which was hardly likely to be visited by many people for its architecture.
Scott's design was for a large building with a central tower capped by a broach spire and the robust details of his other ‘square abacus’ works. The tracery was simple plate tracery designed by Street as Scott’s assistant. Mouldings and sculpture were all omitted, perhaps for the same reason that intricate carving was omitted from Alderney, but also because of the likelihood of frost damage. Sketches of St. John's appear in Scott’s own hand, which he would then hand over to his assistants for development. Drawings of it were exhibited at the Royal Academy in 1848. Not only were the drawings sent out, but apparently there were no suitable local materials available so sandstone was sent out from the Giffnock quarry in Glasgow, which until it was worked out in the 1890's, supplied a considerable amount of good building stone for the south side of that city. St. John’s was carried out under the supervision of William Hay but only the nave and aisles were built. The seating, pulpit and altar rails came from Rattee and Kett. The altar table and lectern were by Myers, the lectern carved by Harry Hems. Even the churchyard railings were sent out from London. The truncated cathedral was consecrated in 1850 and, after Feild's death in 1876, it was proposed to complete it as a memorial to him. But nothing happened and it was not until 1880 that Scott's eldest son, George Gilbert, carried on where his father had left off, completing the building, with some modifications, in 1884. However there was another big fire in 1892, which destroyed more than half of the city, including the newly completed cathedral. This was rebuilt again by John Oldrid Scott, following the previous design.
commented in April 1848 about his design:
Under these conditions, most impracticable climate, no available native materials, unpliant ritual, and the need of retaining a parochial character – we think that such a combination, as in the parallel case of a tropical climate, would have justified an attempt at development. Mr Scott has however chosen to build by precedent … it is learned and dignified, but perhaps cold, it displays the artist’s reading and study more than his genius.