Roman Road from St Albans to Silchester

Margary Number: 163

Distance: 45 miles (to Silchester)

I spotted the first stretch of this road from Silchester towards Reading 10 years ago working with the late Hugh Toller and Bryn Gethin. That was on some of the very first Lidar publicly available. Its alignment strongly hinted as to its likely course (more later) but the Lidar coverage was very patchy back then so progress stalled. I left it with Hugh, who had begun work on further researching the route and it appears in the Toller Archive (2016) but unfortunately time was to run out for him.

Fast forward 10 years to Itinera Volume IV (2024) and this road was extensively researched and documented by Nigel Rothwell but working in the opposite direction. Two routes from St Albans were described referred to as R163 and R163C branching off it. The former was a direct one with a Thames crossing near Bourne End and the latter branch taking a more northerly course with a Thames crossing suggested at Mill End. Also available online through YouTube is a similar route described by David Staveley again crossing the Thames at Mill End.

However, these routes were not what I had envisaged 10 years ago. That original logic that I had put my faith in was that instead of a simple straight line the road targets skirting around the River Thames to the north of Henley-on-Thames. That first alignment I found from Silchester strongly suggests it was targeting crossing the Thames at Caversham, an ancient bridging point (AD1163, Wiki). Once across the Thames then crossing the Thames again would make no sense. The only logical course is to skirt around the Thames north of Henley-on-Thames. Admittedly the evidence between Caversham and Henley is not the strongest but the logic of the alignments surely leaves little doubt that this would have been the Roman route.

Historic Counties: Hertfordshire, Buckinghamshire, Berkshire, Hampshire

Current Counties: Hertfordshire, Buckinghamshire, Berkshire, Hampshire

HER: Hertfordshire, Buckinghamshire, Berkshire, Hampshire

Full Route - St Albans to Silchester

A route that has been a puzzle for many years but the logic of where the Roman road surveyor chose to route the road is impeccable and, with hindsight, obvious. The best crossing point of the River Thames was at Caversham. The further upstream you bridge the river the easier it becomes.

Leaving Verulamium

Lidar is not much help in locating the road leaving the city as many of the roads have been robbed of their stone. However, the first 400 metres was recorded by Stead & Rigby in their excavations of 1989.

Beyond there then aerials photographs do appear to show the surviving twin ditches of the load - see below for more detail.

Aerial Photograph - passing Windridge Farm

In two fields the parallel road ditches seem to have survived. These match reasonably well with the first 400 metres know from Verulamium.

Oblique 3D Lidar Images - M1 to Kings Langley

Beyond the M1 motorway then there is some Lidar evidence - not the best but probably the line as far as Kings Langley.

Route Map 1

I have depicted the route dashed as the evidence is intermittent but it is probably the most likely course of the road. Beyond Kings Langley then nothing certain is visible until Langley Lodge.

Oblique 3D Lidar Image - Commonwood

Evidence resumes west of Langley Lodge heading for Commonwood and the River Chess.

Oblique 3D Lidar Image - River Chess

On the west side of the River Chess the road has to climb 50 metres so we would expect the road to dog-leg or angle across the slope. This appears to what has happened here. At first i wasn't so sure but the inset I thinks shows this was the probable route. the road negotiates the contours perfectly.

Route Maps 2 & 3

At the River Chess the road leaves Hertfordshire.

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Last update: March 2025

© David Ratledge