According to Eric Montague, in his Mitcham Histories: 7 The Upper or Fair Green, page 111:
the church was designed by Robert Masters Chart in a style of approximately 13th century … built by Stewart and Sons of Croydon
Dates (also from Montague)
February 1898 – foundation stone laid
1899 – nave and aisles finished
January 1901 – consecrated
1910 – chancel, north transept and south chapel added
The district of St Mark, which covered most of the electoral east ward, was previously part of the parish of SS Peter & Paul, Church Road. It became its own parish in 1905.
It is part of the diocese of Southwark, whose website says:
The church is built of soft red brick with Bath stone dressings and red/orange machine-made, plain clay tiles. There is a copper covered fleche with bell.
The copper at the base of the pointed spire (or ‘fleche’) has become green due to weathering.