When, in 1920, it was decided to break up the diocese of Winchester and create a new diocese at Portsmouth, it virtually went without saying that the new cathedral would be St. Mary's, Portsea. It was older than the only other option, St. Thomas's, it looked like a cathedral and it was in the centre of Portsmouth. We know well enough today that the Cathedral eventually came to be sited at St. Thomas's Church but if it had been suggested to the Anglican congregation at the time there would have been an astonished response.
An important reason why one of the new dioceses should be based in Portsmouth was the recognition that there already existed a church on Portsea Island that was tailor-made for the role of a Cathedral, and that church was St. Mary's. It was nevertheless a close run thing as many of the clergy felt that the Borough of Portsmouth was too decayed and dissolute and would be unlikely to be able to meet the financial needs of a diocese. In practice there wasn't really an alternative, but it still took seven years for the new bishopric to formally gain Royal assent.
In the intervening period a decision on the location of the Bishop's Throne had to be made. It had to be in a consecrated building but it did not necessarily have to be the final choice for the cathedral. All that was needed at the time was to select a temporary or pro-cathedral. At a conference on 21st July 1921, the Rural Dean, Revd. L.E. Blackburne presented the relative merits of St. Thomas's and St. Mary's, noting that the latter was the largest church in the diocese, already managed a large staff, had a parish institute and a large garden, owned further land suitable for the building of a chapter house and was centrally located. It did not go unmentioned that St. Mary's was founded about 10 years earlier than St. Thomas's.
In balancing the argument the Dean pointed out that whilst St. Mary's had been founded earlier the existing building dated back no more than about 40 years whereas part of the fabric of St. Thomas had stood since it's foundation in the 12C. He further noted that St. Thomas's was exceptionally well connected - especially to Gosport and the Isle of Wight, both of which would fall within the new diocese, that it lay in more dignified surroundings and was the civic church of the town.
A vote was taken and although the result had no executive authority it did illustrate that St. Mary's was the overwhelming favourite. The matter could not be moved further at the time as the order dividing the Winchester diocese had not yet been made. Before it could be however, the Hampshire Telegraph launched itself into the debate with an article published on 29th September 1922 which anticipated a forthcoming meeting of the Portsmouth rural deanery in mid October at which a proposal in favour of St. Thomas's should be presented. In the article, the newspaper declared that whilst St. Thomas's "cannot compare with St. Mary's for size and imposing appearance, it is immeasurably more interesting". It prefaced this comment with an observation that siting the cathedral at St. Thomas's would go a long way towards restoring the greatness of the old town.
The meeting took place on 16th October 1922 and was again presided over by Canon Blackburne who expressed surprise that the matter was being brought forward again so soon after the passing of a clear preference for St. Mary's. One after another, members of the meeting stood to reaffirm their convictions that St. Mary's was the only possible choice. At this point a new perspective on the matter was raised by Revd. Norman Higgins, Vicar of All Saints who had been in touch with other new dioceses, particularly that of Coventry, where it had been shown that trying to run a diocese and a large parish under the same roof was proving problematic with diocesan affairs taking precedence over the parish. He pointed out that St. Mary's had a similarly large sprawling parish whilst St. Thomas's parish was small, self contained and easily managed.
The conference barely had time to digest this information before the Revd. W.H. Tate threw a completely new proposal into the debate, namely that the pro-cathedral should be more centrally located and that the only suitable church was St. Michael's. As the meeting had little appetite for taking this suggestion further it was quietly dropped, but in it's place came yet another angle on the matter. The Revd. R. O'Gorman Power said that the decision to award a status of pro-cathedral was not a question of conferring an honour but asking for a sacrifice and that he felt risking injury to one of the finest organised parishes in England was not justified.
Gradually, the weight of the various new arguments took hold with even the Rural Dean saying that he had changed his mind in favour of St. Thomas's, largely on the grounds that if they chose St. Mary's there would be little chance of ever reversing the decision and every chance that the parish would suffer. A vote on an amendment to support the cause for St. Thomas's was taken and carried by 57 votes to 39. The following day a meeting of the Winchester Diocesan Confereence took place at the Green Row Rooms where the arguments for and against were echoed ending with another vote which came out in favour of St. Thomas's again, this time being 48 in favour and 18 against.
The progress towards the creation of the new diocese took a significant step forwards in March 1925 when Canon Lovett was appointed the first Archdeacon of Portsmouth. A few months later he asked the Bishop of Winchester to appoint a commission to look at the whole issue of the new pro-cathedral once more. The commission reported on 20th March 1926 and took the position that if they were being asked to determine which church should be the permanent cathedral then they would opt for St. Mary's but as they had only been asked to consider the case for the pro-cathedral then St. Thomas's offered the most appropriate option.
Archdeacon Lovett responded to the outcome saying that he was sure that St. Thomas's would take on the temporary role as an act of service "without honour or permanence". The appointment of St. Thomas's as pro-cathedral was thereby accepted but it could hardly end the matter as the church was not in a physical condition suitable for a cathedral, however temporary it might be. Sir Charles Nicholson, the Diocesan Architect was consulted and plans were drawn up to enable St. Thomas's to function as a cathedral. Neville Lovett was consecrated as the first Bishop of Portsmouth on 25th July 1927 and St. Thomas's was elevated to it's full status as pro-cathedral at a great service of Hallowing on the 4th October 1927 with the enthroning of the first Bishop following 2 days later.
Over the next few years the full panoply of cathedral status was applied to St. Thomas's and by the 15th July 1935 the final meeting of the provisional Chapter took place at which it was reported that all the processes required by the Cathedrals Commission to provide a Cathedral Council had taken place. This was followed by the first meeting of the Council of Portsmouth Cathedral at which no mention was made of the pro-cathedral: St. Thomas's Church was from that time accepted as the site of Portsmouth Cathedral.
Portsmouth Paper No. 52 - From Parish Church to Portsmouth Cathedral 1900-1939
Portsmouth Cathedral - A Visitors' Guide
'Forever Building' edited by Sarah Quail and Alan Wilkinson