Posted by: Rachel | July 14, 2013

Circular walk in search of South Mimms castle


Anyone who has suffered the congestion on the M25 approaching junction 23 will have noticed the sign for South Mimms, a quiet Hertfordshire village with an interesting medieval church whose tower can be glimpsed briefly when driving east.  It has always been an ambition of mine to discover South Mimms’s other main claim to fame, a motte and bailey castle, marked on the map but whose remaining earthworks are disguised by trees and field crops. The public footpath that passes closest to the site was part of our route for a Friday evening walk, starting at the Black Horse pub.

Turning left from the car-park, we took the public footpath between the houses in the direction of North Mymms. Passing through a small field of rough grazing, we attracted the attention of some ponies, which followed us hopefully before we passed through a gate into the first of three vast fields. The farmer had cut the path with precision through a crop of still-green wheat that covered the flinty soil. The ground rose gently to our left until the wooded brow of the hill, while before us and to the right the wheat crop extended down to AlM. Having emerged from between the houses the open expanse of the hillside was all the more surprising, and gave a view across the valley to Potters Bar.

white variant of Oilseed Rape

pink flower

Unknown pink flowered plant

We passed by a disused chalk pit into a field of acid yellow oil seed rape, shoulder-high, and followed the footpath down to the A1M and along to the footbridge. At this point we paused, partly to try to guess where the castle motte once may have stood, and partly to brush off the golden pollen.  We had noticed that at the edge of the field there were white and pink variants of the oilseed rape, and this led to a discussion about cross-pollination and experiments to produce varieties that are resistant to herbicides through genetic modification.  If you can help identify the pink flowered plant below, please let me know!

At this point we could have crossed the footbridge and continued along the path to North Mymms.  Instead we turned up hill along a well-metalled track, entering the gloomy shade of Mymmshall Wood. The track follows the parish boundary, with evidence of banks, ditches and the remnants of ancient hedges marking the route. Although nearly over, bluebells were still visible at the margin of the wood. After a short distance the path became wooded on both sides; Hawkshead Wood on the right was mainly planted with conifers, and purple flowering rhododendrons had colonised sections of the wood. This prompted two discussions, the first about invasive species such as the rhododendron and the deadly fungus that it carries, and the second about navigation within woodland.

I have always wondered what the problem was with rhodedendrons, which when in flower seemed so beautiful.  After a previous walk I discovered a plant which was on the list of non-native invasive species in the Wildlife and Countryside Act, and was left with the unsettling feeling that the countryside was being invaded by plants which were taking over the rightful habitats of our native plants.  When I started to investigate, I found that the rhododendron was one of the worst offenders.  Over the last fifty years this garden plant has escaped to colonise the entire British Isles, smothering native vegetation and destroying the habitats of the insects, mammals and so on that depend on it.  Its leaves and pollen are poisonous to certain species and when they fall as leaf litter these too contain a poison that suppresses the germination of rival plants.  Worse still, it is a host to a deadly fungal disease related to potato blight that arrived in this country in 2002 and escaped with the rhododendron from nurseries.  It kills beech, oak, sycamore and horse chestnut trees, and more recently is mutating to threaten moorland and mountain habitats, and to destroy bilberries and larches.  So now I understand why management of the spread of rhodedendrons in the wild has become a serious issue (see discussion in the beautifully illustrated book ‘The Wild Things guide to The changing plant life of the British Isles’ by Dr Trevor Dines, Sally Eaton and Chris Myers, Channel 4 Books, 2012).  I don’t think I will ever look at the plant in the same way again!wild rhodedendron

A fork in the path set off our discussion about navigation within woodland.  It seems that most of our group were carrying mobile phones with a GPS navigation system capable of providing precise locations in terms of latitude and longitude, as well as the more traditional map.  There are clues within woodland that can help, for example lichen growing on the sheltered side of the tree trunk or signs of ancient hedge boundaries (see picture below).  The question was how reliable or helpful was a modern aid to navigation.  I have since discovered a free app available for android and apple phones, Livetrekker, that uses GPS to record the route you are walking, allows you to add in photos and videos at positions you decide, and even share your journey with others live or archive the route you have taken (as opposed to the route you thought you had taken!)

ancient remnant of laid hedge

Remnant of laid hedge

There was no danger of being lost on this walk, however, and eventually emerging at The Grange, we walked the last mile down a sunken lane, the banks rising steeply on either side. This section of Black Horse Lane has changed little from the time when it was once the main road north from London to St Albans. Full of twists and turns, and liable to flooding, a new road was constructed by Telford in 1807 which severed the village in two, leaving this Lane as a delightful remnant and reminder of travel in the days of coach and horse.  Our walk finished with a pint in the Black Horse garden, where we were treated to an ariel display by bats flitting between the trees.



  1. So nicely written, and including a pub I know a little of, that I thought this deserved a comment. The lane through Mymmshall wood I know well too, but mainly on two wheels, not on foot. The DEFRA “magic” site has an extract from English Heritage:
    South Mimms motte and bailey castle is situated on an east-facing slope
    overlooking the Mimmshall Brook, about 1.25km north-west of South Mimms
    village. It includes a motte, c.9m in height and 35m in diameter at the base,
    in the north-west corner of a kidney-shaped bailey which measures 125m
    north-south by 110m east-west and is surrounded by a bank and ditch. The
    entrance to the inner bailey was on the south-west side where there is now a
    causeway across a ditch and a break in the rampart. There are traces of an
    outer bailey to the south.
    The castle is thought to have been built by Geoffrey de Mandeville in 1141
    with a licence from Matilda and was probably destroyed in 1143.
    Excavations carried out by J Kent in 1961-5 revealed that a timbered tower had been built on the ground with an entrance on the south and that the motte had then been constructed around the tower with spoil from the defensive ditches. Pottery from the 13th and 14th centuries was uncovered during the excavation and suggests that occupation of the site continued after the destruction of the castle. ”

    If the destruction of the motte & bailey, probably by King Stephen, was 1143 only a year before G d M died. I wonder what the castle was there to defend? it does not seem very large or had a very long existence. Not surprising that there is not much to see now.

    Geoffrey de Mandeville is listed in Sir George Bellew’s “Story of Salisbury Hall” as the owner of that property, in 1086. As the Doomsday Book lists a G d M as Lord of Shenley in 1086, and the G d M, first Earl of Essex died in 1144, it would seem that the de Mandevilles used the Geoffrey and William names for generations. Then, centuries later, Shenley Lodge was separated from the Salisbury estate with Salisbury Hall going to Walter Edward Martin while Shenley Lodge and Pinks Farm passed to Vernon Moritz Martin on the death of their father, Charles Walter Martin. From then a short zig zag of ownership and change of name (to protect the guilty?) brings Shenley Lodge to Manor Lodge School.

    • Glad this reminded you of a route you know well. Thank you for all the information on the castle, which raises so many questions. Perhaps in the winter or when the fields have just been ploughed it might be easier to see the traces of the ditches and banks. Interesting that it was such a brief occupation of the site. As for the location, it is difficult to see why this would be a useful position for a castle, other than it was a very sheltered position within his estate. The Mymmshall Brook was in all probability nothing more than a source of fresh water and fish, since it was unlikely to have been navigable by larger boats. The area around Mimms Wash was presumably as often marshy and flooded as we know from later records, and further downstream the Mymmshall Brook disappears into the chalk swallow holes at Water End, which is also often flooded. The castle does not occupy a commanding position on top of the hill, which remains wooded, but is lower on the south-east slope of the valley. There was not even a major travelling route close by since the medieval road from London to St Albans did not pass this way, However, it must have represented a significant political statement of intent for it to have been demolished by King Stephen. Perhaps it was too close to London or to the lands of St Albans Abbey for comfort.

  2. Just wanted to recommend a book I discovered in the library local studies collection, Derek Renn’s Medieval Castles in Hertfordshire (Philimore, 1971), which includes some intriguing information about South Mimms (or Mymms) Castle. King Stephen created Geoffrey de Mandeville Earl of Essex around 1141, and his estates were mostly in west Essex and included the castles of Walden and Pleshey, and his supporters held the castles of Benington and Walkern. He was granted permission between 1141-2 to build a castle ‘Where he would’ by both Stephen and the Empress Matilda, who was also angling for his support. She also promised him the counties of Hertfordshire and Middlesex, with the bishop of London’s Castle at Stortford thrown in, if he would support her. Geoffrey chose the site at South Mimms which lay on the edge of his manor of Edmonton. He built a castle which was quite luxurious by Norman standards, with a tall, belfry-like tower approximately 35 feet square,entered by a tunnel through a clay bank, plastered inside and roofed with lead. Glazed tiles, pottery, candlesticks, arrowheads, and gilt-bronze bindings were found, so for a time it must have been very comfortable, and secure too, being surrounded by a bank and ditch, with a bridge across to the bailey which was itself surrounded by further banks and ditches. It all came to an end when King Stephen captured Geoffrey at St Albans at Michaelmas, 1143 and refused to release him until he had surrendered all his castles, and as we know, South Mimms Castle was destroyed, the wooden timbers were torn down, and the earth ‘plinth’ on which it stood collapsed leaving a rounded stump of a motte with the ditches mostly filled with earth. Once released, Geoffrey took his revenge by capturing Ramsey Abbey (throwing out the monks), which he then fortified, and used as a base for rebellion against the King. He died in 1144 from an arrow-wound, received while attacking another royal castle. The bailey area of the castle seems to have been occupied into the 15th century judging by pottery finds, and the ditches were further filled in with rubbish. So South Mimms Castle is a testament to one of the most anarchic periods in English history, and Geoffrey de Mandeville seems to have been the embodiment of the warlike spirit of the times.

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