Reading from top to bottom the five parish boundary marks are:
StMO: St Martin Orgar (now combined with St Clement Eastcheap)
StMCL: St Michael, Crooked Lane 1851
StMRNF: St Margaret, New Fish Street 1791
StMM: St Magnus the Martyr 1847
StMM: St Magnus the Martyr 1787
Nearby is a fire hydrant from the 1830s made by Edward and Samuel Poynder, plumbers, of 10 Clement’s Lane, London. Edward Poynder (1782-1853) was Master of the Plumbers’ Company in 1817/18 and 1829/30. His brother Samuel Poynder (1785-1853) was Master in 1821/22 and 1831/32. They were sons of John Poynder (1751-1800), who was Master Plumber in 1794/95.
Below the parish boundary markers are a pipe and valve. These appear to be of the type used by the high-pressure hydraulic power network that covered most of central London at its peak before being replaced by electricity.
On the opposite side of the tower archway is a fossilised hulk of timber which came from the Roman quayside that was built close by in the 1st century.
It is an ancient custom at the season of the Epiphany to mark doorposts of houses, using blessed chalk, with the initials of the Three Wise Men: Kaspar, Melchior and Balthasar, for example: “20 + K + M + B +21”. This can be seen at the entrance to the church. Afterwards the following prayer is used:
O Lord, Holy Father Almighty, everlasting God, we beseech thee to hear us: and vouchsafe to send thy holy angel from heaven, to guard, cherish, protect, and visit, and evermore defend all that dwell in this house. I call upon thy Saints Kaspar, Melchior and Balthasar, to protect my family and my home from every harm and danger, and I place this mark over my door to remain as a constant reminder to us, and to all who enter here, that my house is truly a house of the Lord. O God, make the door of my house the gateway to thine Eternal Kingdom. All this we ask through Jesus Christ, thy Son our Lord. Amen.