Around the year 1180, Jean de Gisors, a wealthy Norman merchant and Lord of the Manor of Titchfield, gave land in his new town of Portsmouth to the Augustinian canons of Southwick Priory so that they could build a chapel "to the Glorious Honour of the Martyr Thomas of Canterbury, one time Archbishop, on (my) land which is called Sudewede, the island of Portsea".

[1] It was given so that they could build a chapel dedicated to the honour of St Thomas of Canterbury, who was assassinated and martyred ten years earlier.

With the restoration of the monarchy in 1660 came the authorisation by Charles II for a collection in churches across the country to raise the £9,000 required to rebuild the tower and nave, which took place from 1683 to 1693.

However, with the Fall of France in June 1940 during World War II, work on the extension scheme stopped and the bays of the nave were blocked off with a "temporary" brick wall.

Nicholson died in 1949 and attempts headed by Bernard Montgomery to finish the structure in the 1960s proved unsuccessful due to substantive failure to find sufficient funds.

[citation needed] Plans published in 1966 by Seely & Paget, with Pier Luigi Nervi as consulting engineer, envisaged a large semi-circular western extension 76 feet wide, constructed of reinforced concrete.

On the rood screen, beneath the nave organ case is a sculpture called Christus by Peter Eugene Ball.

The left side depicts night, with a stylised lighthouse shining on the sea (which alludes to the City of Portsmouth's motto, "Heaven's Light Our Guide").

The north tower transept contains a ceramic plaque of the Virgin and Child by the Florentine sculptor Andrea della Robbia.

[3] Located in the south chancel aisle is a large 1631 memorial to George Villiers, 1st Duke of Buckingham, who was assassinated at the nearby Greyhound Inn.

The cathedral choir consists of up to 20 boys and a 'back row' of adult alto, tenor and bass singers made up of six choral scholars and six layclerks.

[citation needed] The choirs regularly go on tour, with recent European visits including destinations such as Tallinn (Estonia), Stockholm (Sweden), Salzburg (Austria), Berlin (Germany), Gozo (Malta), Ypres (Belgium) and Notre Dame des Neiges in the Alpe d'Huez (France).

[citation needed] The Organist and Master of the Choristers, currently David Price, oversees the Music Department and is assisted by the sub-organist and Michael James Organ Scholar.

The pipes were taken from the John Nicholson organ of 1861 built for Manchester Cathedral, which had been relocated to Holy Trinity Church, Bolton, in 1874; it was rebuilt by Jardine & Co in 1905.

The renovated organ was officially inaugurated in November 2001, by a recital given by Olivier Latry, titular organist at Notre Dame de Paris.

Finally, in 2017, a horizontal Trompete de Maris ("Trumpet of the Sea") fanfare reed division above the main entrance was added.