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Of Locks and Weirs (page 2)

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The Flash Lock


Weirs had the effect of completely blocking what was at that time the most direct and safest route to central southern England. Obviously some way of allowing river traffic to pass through the mill dams had to be contrived. The answer, again dating from the medieval period, was the flash lock. A timber-lined gap about 6m wide was made in the weir, and the flash lock mechanism inserted into the gap.


Brian Drage’s excellent diagram explains the construction and working of a flash lock much better than I can.


Construction and working of a flash lock

Construction and working of a flash lock

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The whole of this mechanism had to be removed at speed against the released current.  No wonder there were frequent accidents.


The ‘pulling’ of a lock was, understandably, fraught with danger for the hands working the lock, who needed both strength and speed, and the bargemen shooting the resulting rapid or being winched up through the lock after the first rush of water had subsided. The first record of a winch in Marlow dates to 1306. This indicates that a flash lock existed at that point, but a flash lock could exist without a winch. Boats could be hauled upstream by a group of men with a rope, but at Marlow the width of the river and the shallow depth of the lock, which meant that boats had sometimes to be pulled over the bottom of the lock and the sill, made a winch necessary. The last flash lock winch on the Thames, thought to have worked on Hurley flash lock, was found on the Wittington estate in the 1980s and restored by Chris Wallis.


The restored Hurley winch at Wittington

The restored Hurley winch at Wittington.

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From an early date Marlow lock had an evil reputation. In 1585 Stow, in a far-reaching survey of London, remarked on…


‘especially one lock, called Marlow Lock, of which there had been great complaints. It was held by one Farmour. The streams there were so strong, and the water had such a dismal fall, that four men within a short time were lost; three whereof were drowned, and a fourth had his brains dasht out. And all the recompence the poor widow had, was that Farmour gave her five shillings. But beside the danger, it was very expensive to the poor bargemen, the millers selling the water in the stream for above £300 a year.’


Nothing new about expensive season tickets, then! It seems, as Farmer was recompensing the widow, that it was one of his own men who was brained. The likelihood is that most of the deaths on the lock were of local men. There is no record of a winch on the far side of the weir-pool, so when barges had to be poled down through the drained lock, the mill hands must have gone into the water with ropes and rollers to pull it through. As barges increased in size and weight there must have been considerable scope for accidents. In 1632, in a poem about the Thames, John Taylor said,

The Marlow locke is worst, I must confess,

The water is so pinched with shallowness.

Although the water was shallow, the current was so rapid and strong that the area became known as Marlow Race, of which another poet said that it…

…hath made many a Child to weepe.
Their mothers begg from dore to dore
Their fathers drowned in the deepe.


Shooting a small flash lock

Shooting a small flash lock

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This modern drawing of a boat shooting a much smaller flash lock than Marlow’s captures the effort involved in keeping the boat straight.


Who was responsible for this vast piece of medieval technology? The ware and flash lock, together with the winch at the bottom of St Peter’s Street, formed part of the mill estate.


The ware, flash lock and Marlow wharf

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Another of the Marsh brothers’ Victorian photographs, taken from the lower bank of the weir-pool, shows the upper part of the weir, with the flash lock on the right.  Behind, at the bottom of St Peter’s Street, is Marlow wharf.  In 1871 all the cottages shown here were demolished to build Old Bridge House.


This embodied a violent clash of interest. The miller wanted to run his mills regularly in order to make money, but every time he pulled the flash lock it took at least forty-eight hours for the river to rise again to a useful level. Hence the vast charges made to Elizabethan barge-masters for use of the lock. Originally the mills had belonged to the manor, but ownership of the two in the town had been passed to the miller. At the beginning of the fourteenth century, in a sudden rush of blood to the head, he gave them both to St Thomas’s Hospital in return for an indulgence reducing his time in Purgatory by twenty days. By 1530 John Leland reported that the mills, as well as grinding corn, were pressing linseed for oil and making thimbles. At the Reformation they were sold off to a wealthy local family, the Farmers, who unfortunately became recusants and had eventually to sell the mills to pay their fines for non-attendance at church. Several generations of the Ferrars family owned and ran them, until in 1755 the wife and daughter of the last miller put the whole estate up for sale again, leaving us this magnificent estate plan.


Mill estate map

Mill estate map

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The map drawn up for the sale of the mill estate by Elizabeth Ferrars in 1755.  It shows the full extent of the mill lands, including the original miller’s house, approximately on the site of The Garth, and their holding in the Common Field.  Please note that Duck Lane did not exist; St Peters Street did.


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