Milepost 17 Metres South of Number 306

This is a milepost located 17 metres south of Number 306 in Mountnessing, dating from the 18th century to early 19th century. It is made of limestone and features a cast-iron cover plate. The milepost has a triangular shape with one vertical surface facing south embossed with "Chelmsford 8" and another facing east embossed with "Brentwood 3". The back is chamfered to a sloping surface above, which faces southeast and is embossed with "To London 21 Mount-neysing". The milepost has a crack that runs from side to side, which has been repaired with two plates at the back and four bolts near each edge.

Historically, the road from Shenfield to Ingatestone was one of the first turnpike roads in Essex, adopted by the Essex Trust in 1695. The erection of milestones became mandatory from the 1760s. This specific design of the cover plate was introduced by James McAdam and adopted by the Essex Trust in 1819, following a recommendation from Lewis Majendie of Hedingham Castle, to reduce the costs associated with re-cutting inscriptions on the stones and to improve clarity. The milepost is shown on Chapman and Andre's map of 1777 and Cary's map from 1790. It is also illustrated in Edwards' work from 1978, noting that the cover plate was separating from the stone behind it, which was already cracked and repaired. The stone retains the same shape and has the inscription "London XXI" on the upper surface, while other inscriptions are concealed. According to Booker, mileages expressed in Roman numerals indicate that this milestone is from the 18th century.