The original windows of the church were made of plain glass. As the church was enlarged with the addition of the north and south aisles and the baptistry, it was richly endowed with stained glass given in memory of men and women whose untiring efforts brought so many benefits to the parish. Most of the windows show biblical scenes, and these helped to teach the people about religion in the days when many of them could not read. The separate pieces of glass each have their own colour and are set into strips of lead. The colours in early stained glass were each thought to have a meaning; for instance, red meant divine love, white - divine wisdom, yellow - faith, and so on.

'The Ascension'

Sanctuary
The great east window above the altar in the Sanctuary represents the 'Ascension', flanked by representations of the 'Nativity' and the 'Visit of the Magi'. The insciption reads: "In memory of Thomas Emeas born 1814, died 1875". See the sanctuary windows.

"The chancel, with its admirably proportioned arch and triple lancet windows, gained vastly in effect from the introduction of stained glass of geometrical pattern to the eastern window, an offering from the Rev. John Fitz Wygram". The late east window will be removed to the west end of the church and a new beautifully stained window by Baily of London, of three divisions (one the gift of G. T. Ewens, chapel warden) will take its place.

Mrs. Emma Bligh, Henry Bligh’s first wife, is commemorated by windows on the south side of the sanctuary. One window represents 'The Last Supper' and bears the inscription "Love One Another", and the other represents the 'Stoning of Stephen' with the inscription "Faithful unto Death".

Chancel
The memorial window on the north side of the chancel was erected in 1921 and commemorates the Revd. C. R. Job. It represents 'St. John the Evangelist' and bears the inscription: "To the Glory of God and in the Memory of Charles Robert Job, Priest Vicar of this Parish AD 1893-1914. Erected by Parishioners and Friends". See the chancel window.

'The Transfiguration of Christ'

Nave
The Great West Window, a memorial window to the Revd. Fitz Wygram, depicts the 'Transfiguration of Christ'. It is at the west end of the church, above the porch, the original of which was also built in his memory. £500 was collected by public subscription for these memorials. It bears the inscription: "To the Glory of God and in loving remembrance of Fitzroy John Fitzwygram, First vicar of this parish, 1863-1881. This window is erected by his parishioners and friends, 'A faithful man and feared God'. He entered into rest August 13th 1881." See the nave windows.

North Aisle
The windows in the north aisle were originally plain glass and were later replaced by ones in stained glass, dedicated to parishioners who were well known at the time. The first double window (east end) representing 'David Rex' and 'Sancta Cecilia' was installed by public subscription to the memory of the first organist Mr. William Singleton in 1877. The brass plaque below is inscribed: "These two windows were erected by the Grace of God in loving memory of William Singleton, first organist of this Church. Born January 18th 1852, died April 15th 1877. F.I F.P.S E.S."

The second double window was installed in 1889 and represents 'Centurion kneeling "Looking unto Jesus"' and 'Jesus carrying the cross "May they rest in Thy peace"'. The brass plaque below is inscribed: "To the Glory of God and in loving memory of Major General William Friend Hopkins CB., also of Jessie his loved and faithful wife who entered into their rest March 23rd 1885 and September 8th 1888. This window is erected by their sorrowing daughter. 'For so he giveth his beloved sleep'."

The third double window was also added in 1889 and represents 'Mater Dolorosa' and 'Mater Purissima'. The inscription reads: "To the Glory of God and in Loving Memory of Florence Foster, born 26th January 1846, died 18th January 1899".

The fourth double window was installed in 1907 by Mrs. Sale Hall, a former resident in the parish, in memory of her late husband. The figures in the window represent 'Faith' and 'Hope'. The inscription reads: "To the Glory of God of the living and the dead, and in loving Memory of James Frederick Hall who entered into his rest November 21st 1905, aged 63. These windows are erected by his sorrowing widow. 'I know that my Redeemer liveth'." Read the article A New Stained Glass Window.

The fifth double window was added in memory of Lieutenant Colonel and Mrs. Butler in 1914 and represents ‘I am the Resurrection and the Life’ and ‘Melchizedek’, the latter meaning ‘king of righteousness’. It was given by their daughter, Miss Alice Butler, and was unveiled in April 1914 with a ceremony which included an organ recital. "To the Glory of God in loving memory of Edward Charles Butler Brevet Lt Colonel 36th Foot who died at Peshawur May 21st 1868 aged 50 years and of Frances Guadaloupe Felipe Maria Butler born April 19th 1825 who passed in her sleep October 30th 1913 aged 88 at Hampton Hill where she resided for 44 years, given by their youngest child ACB R.I.P."

The sixth double window was erected by the family of the late Mr. Pemberton, formerly of Hampton. It represents 'Zacharius, "Blessed be the Lord God of Israel"' and 'Saint Elizabeth "Blessed are they which do hunger and thirst after righteousness for they shall be filled"'. Zacharias and Elizabeth were the father and mother of St. John the Baptist. "In loving memory of Charles Pemberton, born 29 Sept 1814, died 6 Sept, and of Jane his wife, born 12 March 1825 and died 18 March 1888, this window is erected by their surviving children March 1900". Read the article A New Stained Glass Window.

A small window, given by the Communicants' Association and others, was in place by Easter 1900. It was installed at the west end of the north aisle with the work being done by Messrs. Arthur Moore & Co. The inscription reads: “Go ye also into the vineyard. To the Glory of God by the S. James Communicants Association Easter 1900” Another window with the inscription “Follow me and I will make you fishers of men. To the Glory of God, by the Communicants Guild 1910” was put in the west end of the north aisle by the Communicants’ Guild in 1910. See the north aisle windows.

'The Good Samaritan'

South Aisle
On the south aisle are a series of handsome windows based on the Parables, given in memory of the first vicar by his wife and her mother, Lady Ward. The choice of the parables 'The Sower and the Seed', 'The Good Shepherd' and 'The Good Samaritan' is a particularly apt memorial to the man and his work. In 1911 the churchwardens decided to put a new upper window in the south side of the church to correspond to the north side, thereby improving the light and also the ventilation. Later, other such upper windows were added.

The first double window (east end) represents the 'Parable of the Good Samaritan'.

The second double window represents the 'Parable of the Lost Sheep' and has the inscription: "I have found my sheep which was lost. St Luke. He shall gather the lambs with his arm. 1 Isaiah".

The third double window represents the 'Parable of the Sower and the Seed and the Angel Reaper' and has a brass plaque inscribed: "This window is erected to the Glory of God and in memory of Fitzroy John Fitz Wygram first vicar of this parish 1882 by EEW".

The fourth double window represents the 'Parable of the Wise and Foolish Virgins'.

'St. Mary, Mother of the Lord'

The fifth double window represents the 'Parable of the Prodigal Son' and has a brass plaque inscribed: "These two windows are erected to the Glory of God and in memory of Fitzroy John Fitz Wygram who entered into rest 13th August 1881 A.F."

Years of sunlight on these beautiful south-facing windows had taken their toll and badly damaged the leading, resulting in rainwater leakage in the surrounding masonry. In the spring of 2005 they were removed and taken to the Chapel Studio in King's Langley, near Hemel Hempstead, to be repaired and restored. Read the article Stained Glass Window Refurbishment. See the south aisle windows.

Baptistry
Two of the windows on the west side of the baptistry were given in memory of Mrs. Fitz Wygram. The one representing 'Anna' bears the inscription: "To the Glory of God and in memory of Alice Fitz-Wygram widow of the first vicar of the parish born April 8th 1839 entered into rest March 9th 1912. Erected by her relatives" The other one, representing 'Simeon', was "To the Glory of God and in memory of Alice Fitz-Wygram widow of the first vicar of the parish born April 8th 1839 entered into rest March 9th 1912. Erected by friends and parishioners". The third window, in the centre, was given in memory of Revd. Bligh in 1913 with the inscription: "St. Mary, Mother of the Lord. To the Glory of God in memory of Hon Revd. Henry Bligh, vicar of this parish AD 1881-9. Entered into rest March 4th 1905. From his wife and son." These three memorial windows were unveiled on St. James's Eve, 1913.

The windows on the north side of the baptistry were given in memory of Revd. Coad Pryor in 1923 with the insciption: "To the glory of God and in Loving Memory of Richard Coad Pryor, Priest. Vicar of this Parish AD 1914-23. Erected by Parishioners and Friends". The left panel represents 'I am the Good Shepherd' and the right panel represents 'I am the Light of the World'. See the baptistry windows.