The following year he designed a new chancel for St John's church and in 1884 was engaged to sketch the memorial window dedicated to Bishop William Williams, Waiapu's first bishop, who died in 1878.
Mountfort also designed Anglican churches further afield: the simple yet picturesque wooden St Paul's in Wairoa, 1879 (demolished c1958); the addition of the chancel and vestry at St Luke's Havelock North, 1881; and the wooden St Matthew's Church, Hastings, 1885.
In 1883, rather than extending St John's Church, which had become too small for the size of the congregation, it was decided to build a cathedral befitting the centre of the Anglican diocese of Waiapu and the seat of the bishop. The diocese extends from the East Coast including Tauranga, Rotorua, Taupō, Gisborne, Hastings and Napier, across the Ruahine Ranges to Woodville.
Mountfort was the obvious choice as architect and by June 1886 he was at work on the plans. On September 29, 1886, Bishop Edward Stuart laid the foundation stone, which the Daily Telegraph heralded as "a red letter day in the history of Napier".
The proposed new cathedral very quickly became the centre of controversy, particularly around the use of brick rather than wood as a building material.
One concerned Napier resident raised the question of using such materials in a volatile earthquake-prone area. Others questioned the strength of the concrete produced for the foundations, particularly as the enormous shell of the building would be carrying an exceptionally heavy slate roof.
To combat this problem, the buttresses, which were usually on the outside of a building, became an integral part of the interior. It was calculated they would take the weight and pressure of the immense roof and meet the stress imposed on the walls if an earthquake occurred.
The extraordinary large cathedral was an incredible undertaking for a small provincial town. It was constructed using 452,000 locally made red bricks. The limestone for the dressings and horizontal bands (which served to soften the colour of the brick) came from the South Island. Hawke's Bay forests provided the native timber for the interior ceiling and fittings.
Mountfort's interior design included a nave, chancel and transept, with an organ chamber south of the chancel. The ceiling was an open timber structure, having no central beam.
Praised in the newspaper was the roof, which was covered in red and green slates arranged in patterns and finished at the skyline with a perforated ridge. Another special feature mentioned was the skilful use of bricks on the exterior walls "moulded in varied and appropriate patterns".
The Williams Memorial Chapel (in the sketch St Augustine's chapel), located on the east side of the north transept was conceived as an integral part of the cathedral, although not built until 1902. The absence of the Williams Chapel at the time of consecration was regretted for "its greater richness and comparatively lower height, would give scale and measurement to the mass of the higher building". When completed, it housed the stained-glass window designed by Mountfort in 1884.
The date of consecration was set for December 20, 1888 at 10.30am. The choir had doubled in number to 100 when "Mr Spackman, the talented organist of St John's, decided to strengthen it by the admission of ladies".
They practsed assiduously and reportedly achieved a "high standard of excellence". At the official start of the consecration, Bishop Stuart "took his pastoral staff in his right hand and knocked at the door saying 'Open Ye the Gates'". More than 1000 people attended this auspicious occasion, which the newspaper described as "an imposing ceremony".
The Waiapu Cathedral stood for a mere 43 years. On February 3, 1931 at 10.47am, an earthquake measuring 7.8 on the Richter scale destroyed the building and it became a pitiful pile of bricks and debris. The War Memorial Cross stood as a lonesome sentinel to signify its demise.
• Gail Pope is social history curator at the MTG.