In 1856 a scheme was started for getting the Abbey Church raised to cathedral rank, and also for restoring the fabric. Mr. (afterwards Sir) Gilbert Scott was appointed architect, and was empowered to do what he thought most pressing as far as funds would allow; the flat roof of the north aisle was renewed, drainage attended to, and foundations strengthened; the floor at the south end of the transept was lowered—it will be remembered that it had been raised in 1692—the vaults were filled with concrete, and the floor repaved. The presbytery was repaved with tiles copied from some old ones. The Georgian fittings were removed to the nave; fragments of the tabernacles, which we now see over the doors leading from the aisles into the presbytery, having been discovered, the tabernacles were reconstructed of the old with some new material. But more important work had to be undertaken in 1870. On Sunday, July 31st, the sound of cracking was heard in the tower, and Mr. J. Chapple, the clerk of the works, went up the next day to London to see Scott and asked him to come down at once to examine the tower; plaster was put over the crack to see if it was increasing or not. There were soon signs that the mischief was getting worse, and Scott ordered the tower to be shored up with timber, and temporary brick walls to be built below it. It seemed that the rubble of the eastern piers had been made of mortar which had turned into dust, and that a big hole had been cut in the south-eastern pier. This, according to Lord Grimthorpe, had apparently been done with the intention of demolishing the tower, probably soon after the time of the dissolution of the monastery, for the hole contained timber shores which were sufficient to support the tower while the workmen were enlarging the hole, but which were probably intended to be set on fire and burnt away, thus allowing the workmen to escape before the tower fell. This wood was found partially decayed, and probably to its state the settlement of the tower was partially due. The hole was, by Scott's direction, filled with bricks laid in cement, and cement was poured in to fill up all the interstices; some of the decayed rubble was cut out of the piers and brickwork put in to take its place: the walls were tied with Yorkshire flagstone and iron rods, and were grouted with liquid cement wherever possible. It was an anxious time for those in charge of the work; it was only after many days and nights of incessant labour, that they felt sure that the sinking of the tower was arrested and that the new work was holding up the weight.

In 1875 it was discovered that the south-west clerestory was beginning to crumble away. Lord Grimthorpe had this shored up at his own expense. A new committee was soon after this appointed, and in March, 1877, a faculty was granted to this committee "to repair the church and fit it for cathedral and parochial services." The first Bishop, Dr. Claughton, who up to this time had been Bishop of Rochester, choosing the northern of the two parts into which his diocese was divided, was enthroned as Bishop of St. Albans on June 12th, 1877, and on the following day the restoration of the nave was begun. The church was in a very bad state: the weight of the roof and injudicious repairs had thrust the clerestory walls about forty inches out of the vertical plane. There was much controversy at the time as to what should be done, and in the middle of it Sir Gilbert Scott died, in March, 1878. In May, however, the roof having been lifted, the leaning walls were forced up into a vertical position by hydraulic pressure. Some of the restorers were in favour of retaining a flat roof; others advocated putting on a high-pitched one again, raising its ridge to the height of the original Norman roof, as indicated by the weather marks on the tower. Fortunately the latter course was adopted; fortunately because the church, seen from the outside, lacks height in proportion to its length, and the ridge of the roof now visible above the parapets has given it some of the extra height it so much needed. The subsequent raising of the transept and presbytery roofs on the other three sides of the tower was necessitated by the raising of the roof of the nave.

Lord Grimthorpe drew up a list of "symptoms of ruin," twenty-two in number, which it would take too much space to reproduce here; but unless his account is exaggerated, it would seem that scarcely any part of the building save the tower could be looked on as secure. He applied for a new faculty which would give him unlimited power to "restore, repair, and refit the church." This faculty was granted, and he exercised his powers to the full; and as a result, though the church has been made sound and secure, probably for many centuries to come, yet many of its most interesting features have been destroyed, the most terrible damage having been done in the transept.

The west front which he rebuilt, though not altogether satisfactory, yet is greatly superior in design to his subsequent work at the south and north ends of the transept. These originally had corner turrets, octagonal in plan; these turrets were pulled down and square ones, finished by pyramidal caps, put in their place. The entire south front of the transept was pulled down and rebuilt, and a new window consisting of five lancets occupying its whole width inserted. The central light rises high into the gable and above the level of the inner ceiling. The lancets on either side are intermediate in height between the central and side ones when they are seen from without, but when seen from within the tops of all are of the same height, as they could not be raised above the level of the ceiling. The parts of the three middle lancets seen from without above this level are backed up with black felt across the ceiling, and their upper parts light the space between the ceiling and the high roof. This window is a feeble imitation of the "Five Sisters" of York, and is utterly out of place in the narrow transept at St. Albans; but bad as this south window is, the one at the north end of the transept is worse. Here Lord Grimthorpe inserted a circular window, the design being such as a child might make who was given a sheet of cardboard with a large circle drawn on it, which he was requested to cover symmetrically with a number of half-crowns, shillings, and sixpences. Another piece of unnecessary alteration was the destruction of the slype at the south end and the re-erection of its disjointed members as curiosities in the new work, its western doorway, with an added order, having been let into the centre of the south wall of the transept, and the arcading placed in two different positions.

More satisfactory is the work in the Lady Chapel and the space sometimes called the antechapel; here the old carving had been terribly mutilated by many generations of schoolboys, and the new work which has been put in is good of its kind, and distinctive in its treatment. Lord Grimthorpe vaulted the Lady Chapel in stone. Much other work was done by him in various parts of the building. He rebuilt the clerestory windows of the presbytery and some of those in the nave; introduced windows into the blank walls at the western part of the nave, both on the north and south, for which he deserves commendation, as the original reason for no windows having existed here was only that the monastic buildings, now destroyed, abutted against the south aisle of the nave, and the Church of St. Andrew stood on the north side; when this church was pulled down a plain wall was built, and the thrust of the roof had forced this and the original wall on the south side outwards, after the buildings which had acted as buttresses had been removed.

One piece of modern restoration was not done by Lord Grimthorpe, namely that of the Wallingford screen behind the high altar. The statues on this having been destroyed and the screen itself damaged, Mr. H.H. Gibbs, now Lord Aldenham, offered to restore it, working under Lord Grimthorpe's faculty. After a time a dispute arose between them, chiefly over the introduction of a statue of Christ on the Cross in the centre of the screen, and the erection of an altar with a stone top below it. This led to a lawsuit, the final result of which was that Mr. Gibbs was allowed to finish the screen in his own way, but not to do anything to any other part of the church, a thing he wished to do. The altar is not yet in position; when this is placed where it is intended to stand, the work of restoration will be complete, and nave, choir and presbytery, and Lady Chapel will then alike be capable of being used for service, forming in reality three distinct and fully fitted churches under one roof, the retro-choir being intended for use as a chapter-house whenever a chapter shall be created.