The reredos is wholly built of Derbyshire alabaster. It is designed with a moulded and carved retable. The octagonal flanking towers are carried up to the full height of twelve feet, and have pierced panels of delicate tracery patterns and single buttreses and finials. At each end are large diagonal shafts with crocketed finials semi-attached to the towers and forming slight wings.
Above the retable, the large central panel, with its detatched shafts or arcade in front, depicts in sculptured relief 'The Last Supper', a reminder of the central act of the Church's remembrance and participation in Christ's salvation. Jesus is shown sharing the bread and wine with his disciples, "Do this in remembrance of me". At the edge is a man with a money bag who is about to slip out and betray the Lord.
Below the panel is a series of seven smaller panels with carved heads, each panel containing carved roses and the monogram I.H.S. alternately. On each side of the centre, and adjoining the large towers are two niches, superimposed and containing figures, in relief, of the four evangelists. The cornice above the canopies has carved roses and a pierced cresting in the form of an inscription, which reads as follows: 'I am the Bread of Life, he that cometh to Me shall never hunger.'
Behind the reredos and against the east wall oak panelling has also been provided by the Mayor. This has been carried to a height of 8ft. 6in., and has four heights of panels, the two upper rows being enriched with linen fold patterns in relief, and carved roses in the centre of the lower row of panels. The cornice is carved with a vine pattern, and has the following inscription in raised letters in old English type: 'As often as ye eat this bread and drink this cup ye do shew the Lord's death until he come.'
A more detailed description is given in a report of the Dedication originally published in the Hertford Mercury on 4th April 1914.
You can read a copiously illustrated and detailed report of the restoration work done in early 2019 here.