Fr Tremenheere left St Agatha's in 1911 and was replaced by Fr C W Coles who had served at St Agatha's as a Curate in the 1890's before entering the Royal Navy as a chaplain. Fr Coles long and heroic ministry spanned two wars and an economic depression. The tide was now turning against costly building projects and decorative schemes, as can be seen in numerous unfinished towers and aisles in late 19th century churches across the country. Certainly the time taken to complete the baldacchino suggests a slowing, if not a substantial reduction, in the funds available for such work at St Agatha's. And even before the First World War and its aftermath a major source of financial support had come to an end when, in 1908, the Winchester College Mission moved to the church of St John the Baptist, Rudmore.

In 1919, Ball designed a splendid silver fronted altar for the Lady Chapel as the First World War Memorial: but it was destined to remain on the drawing board and one of the Portland stone capitals was carved instead. A similar fate befell the sumptuous plans for the baptistery beneath the south-west tower, drawn-up by Victor Heal, which was to have been lined with marble and alabaster entered through wrought iron gates. A particularly imposing feature of his plan was a shrine altar supporting a full-length figure of St John the Baptist, in marble. If financial constraints halted some schemes then the disappearance of Sumner, to the New Forest, effectively ended others. His coloured cartoon for the decoration of and southern arcades showing scenes from the life of Christ give a tantalising hint of a glorious interior which would have been wonderful to behold. Sumner died in 1940; the same year in which the bombs destroyed St Agatha's parish.

Smaller targets were reached. Handsome altar ornaments graced the two main altars. The statues of Our Lady and St Agatha were introduced and the nave capitals were finished. By the 1930's, the Anglo-Catholic Movement was in full swing with High Masses at the Albert Hall and White City Stadium attended by thousands of the faithful. St Agatha's was a veritable Anglo-Catholic shrine forever associated with the famous Fr Dolling and attracted people from far beyond the streets of Landport who flocked to witness feasts, such as Corpus Christi, celebrated with great splendour.