The High Altar Sanctuary is also the memorial chapel for those who died in the First World War, their names are recorded on two tablets the first is on the left hand side and the second on the right.

As early as November 1917 the congregation of St. Alban’s had met and decided that some fitting memorial of a permanent nature should be erected in the church to the memory of those many members of the church family who had made the great sacrifice in the World War of 1914. Accordingly a committee was set up to make suggestions as to the form such a memorial should take, the committee unanimously recommended a reredos, a painting eight feet by three feet immediately above the Altar (High Altar) and panelling to a height of seven feet from the floor on the north and south sides of the Sacrarium. These three suggestions were adopted and carried out. An appeal for funds was launched by the War Memorial Committee as soon as its proposals had been adopted, and so gratifying was the response that the decoration was completed by 20th June 1920 on which date it was dedicated by the Bishop of Chelmsford.

The first impression one receives of the reredos is its grandeur, covering as it does the whole of the eastern wall of the chancel. The high reredos is not a common feature of English ecclesiastical ornamentation although examples may be seen in the Cathedrals of St. Albans and Winchester. The reredos is of wood. It is gilded and painted and contains seven large niches which hold the following statues; at the top Christ Triumphant in the centre, St. Mary of Prittlewell on His right holding a model of Prittlewell Church, the mother church of the parish, and St. Alban on His left holding a model of our own church. Immediately beneath these three is a representation of the Nativity flanked on either side by the four Patron Saints of the British Isles, St. George of England, St. Andrew of Scotland, St. David of Wales, and St. Patrick of Ireland. Immediately above the High Altar and below the representation of the Nativity is a painting of the Annunciation. The panelling on the north and south sides of the Sacrarium is of cypress wood with special panels containing the names of the parishioners and members of the congregation who fell in the Great War of 1914.

The fine sense of proportion and balance, the exquisite blending of the colours and the ornate design of the nitches and figures, all combine to produce a feeling of beauty and holiness and give to the church what is perhaps its richest and most beautiful piece of interior ornamentation. The whole of the reredos and panelling was designed by Sir Charles Nicholson, the architect of the church. The design, leading both eye and mind heavenward, it is a fitting resting place for the Reserved Sacrament.

The total cost of £900 was raised entirely by direct money gifts of the congregation.