This lost church was dedicated to St. Margaret the Virgin of Antioch and stood on the corner of Monument Street and Fish Street Hill. There were two fish markets in the city in medieval times – one near St Mary Magdalene Old Fish Street and St Paul’s in the west and one just up the hill from London Bridge in the east. Today you will find two streets named ‘Old Fish Street Hill’ and ‘Fish Street Hill’ in the west and east respectively. This eastern street was previously known as ‘Bridge Street’ as it ran straight down past St Magnus the Martyr to old London Bridge. So the first mention of this church is as “Sci Margaret us Pont” in 1199 – meaning St Margaret by the bridge – and later “St Margaret in Breggestrate” in 1275, which became St Margaret, Bridge Street.
The fish market was right outside the church walls. A City ordinances dictated that lampreys brought over from France ought to be exposed for sale immediately after arrival under the wall of St. Margaret’s Church in Bridge Street. Pilgrims heading out of the city over the bridge would also leave gifts at the church in the hope of a good journey. John Stow in his survey of London of 1598 called it “a proper church” but noted that it had no monuments. However, it did have a remarkable collection of relics including a piece of the holy cross, fragments of the Virgin Mary’s clothing, part of the bush of Moses, some bones of St Andrew, a tooth of St Brigid and part of Christ’s crib. These precious relics were among thirty listed in a Cartulary from 1472 – although whether they were genuine seems doubtful.
We know what the church looked like from the Wyngaerde panorama of 1543 and the Agas map of 1560 shown here. The church was destroyed in the Great Fire of 1666 (which started twenty yards away in Pudding Lane) and not rebuilt, so the parish was united with nearby St. Magnus the Martyr. Hollar drew a panorama of the City after the fire and you can see the burnt remains of St Margaret on that drawing.
You can still find traces of the lost church of St Margaret New Fish Street today. There is an old parish boundary marker that has been relocated to the wall of St Magnus the Martyr and a stained glass window commemorating St Margaret inside that church. A blue plaque on the wall near the Monument marks where the church stood and an old fire hydrant with St Margaret’s initials is still fixed to the base of that structure. Lastly, the human remains from the churchyard were reburied in Brookwood Cemetery with a fine memorial including remains from the churches of St Magnus the Martyr and St Michael Crooked Lane.
The wikipedia page for St Margaret New Fish Street is here.