Tun Bridge carries Garnier Road (formerly known as Bull Drove) over the Navigation and consists of a single concrete arch built in 1926 to replace the earlier wooden bridge. There is a car park on the east bank just south of the bridge. In September 2019, the Handlebar Café was opened adjacent to the car park catering for bikers and walkers.
Tun Bridge to St Catherine’s Cottage
From here to St Catherine Lock, the way south is now restricted to the towing path on the east bank and, in places, it is quite narrow although some work has been done in recent years to widen the path. The path is backed by a fairly steep bank but above this there is a public bridleway parallel to the canal and a few yards to the east. This is Twyford Lane and is the remains of what was once a road from Winchester to Twyford and Portsmouth. It is now part of the long distance path called the Itchen Way which runs from the source of the River Itchen south of Cheriton to Southampton Water. This in turn is backed by the site of the former Didcot, Newbury and Southampton Railway. Before the M3 was constructed, the notorious and busy Winchester Bypass lay beyond the railway.
The Winchester Bypass was constructed during the 1930’s and was one of the first fully dual carriageway bypasses in the country and opened fully to traffic on 1st February 1940. In February 1937, the railway and Twyford Lane were moved westwards up to about 60 feet (18 metres) nearer to the Navigation to accommodate the new bypass as it passed below St Catherine’s Hill. But with the completion of the M3 in 1994, the bypass and some of the course of the railway have been eliminated and the environs of the waterway are peaceful once more.
From Tun Bridge to the M3 at Hockley, as part of National Cycle Route 23 from Reading to Southampton and the Isle of Wight, Twyford Lane has now been tarmaced and is shared by cyclists and walkers.
About half way along Twyford Lane between Tun Bridge and the lock is a sculpture of a barge. This is called “The Pausing Place”, was designed by artist Abigail Downer and was unveiled in August 2011 to give walkers a place to stop, sit and rest. Three metres long, it’s carved from Portland stone and bears the names of some of the bargemen who worked on the Navigation between 1710 and 1869. It is not, however, right beside the Navigation.
St Catherine’s Cottage to St Catherine Lock
Today there are no buildings on the west bank of the Navigation - just views over the water meadows towards St Cross. However, there once was a modest Victorian dwelling close to the Navigation nearly 200 yards north of St Catherine Lock. Called St Catherine’s Cottage (it was also known as Halfway House), is just visible in the photo of the mill shown below. The last tenant of the cottage, a Mr Marriner, died in 1956, and the cottage, already derelict, was sold in 1957 at the same time as the meadows to the west. It was demolished and no trace of it now remains.
Just before reaching St Catherine Lock, there used to be a bridge under the railway and bypass, but this was removed in 1994/5 opening up a vista of Plague Pits Valley and St Catherine’s Hill rising over 200 feet above the canal. The fort on top of the hill was constructed in the 3rd century BC but deserted after it was sacked in the 1st century BC. A Norman chapel dedicated to St Catherine was built in the 12th century but no remains are now visible. The hill is now a nature reserve.
St Catherine Lock
A mile from Black Bridge lies the summit lock of the Itchen Navigation which begins the descent of about 105 feet (32 metres) to the sea. Usually known by the name St Catherine (or St Catherine’s) Lock, an Ordnance Survey map of 1870 gives the more prosaic name “Lock No 1”. Like the majority of locks on the waterway, it was turf-sided as was customary on waterways built in the 17th and early 18th centuries. Turf-sided means that the water within the lock chamber was retained by sloping earthen or “turf” banks rather than the stone or brick walls that are usual on more modern waterways. That these banks often leaked did not matter greatly as the river would normally supply enough water. Usually, the only brickwork / masonry to be found in such locks is at each end where the lock gates were hung. On the Itchen Navigation, at most of the locks, the top and bottom gates were about 100 feet apart.
A modern sluice has been built across the head of the lock in place of the top gates to retain water in the section of canal above. The lock is very unusual (possibly unique) in that during the middle of the 19th Century, there was a sawmill on the west side of the lock. This mill was powered by a waterwheel that drew its water from above the lock gates, discharging it into the lock chamber. The conserved remains of some of the brickwork for the wheelpit can still be seen, on the offside, just downstream of the older brickwork associated with the top gates.
The lock received attention as part of the conservation works carried out in 2010 during the Itchen Navigation Heritage Trail Project which was partially funded by a Heritage Lottery grant. This involved clearance of some trees and other vegetation that was threatening the structure. In the areas of the top and bottom gates and the mill wheelpit, crumbling brickwork was replaced or consolidated, re-pointed, and tied back to the banks behind. Three ‘bat bricks’ were installed in the SE gate pier to mitigate for the loss of any potential bat roost sites. Further details of the repairs together with photographs see this report (3.74MB) made as part of the project.
As seems to be the case in projects such as this, however, little or no consideration appears to have been given to ongoing maintenance of the works done. As a result, since completion of the project in 2012, they have started to suffer from neglect.
As part of this project, an information board was installed telling a little of the local history. Unfortunately, the drawing in particular does not give a realistic portrayal of the lock or the barge within it. See problems with drawing.
The following problems with the information portrayed in this drawing have been identified. Whilst many of these points are not major individually, the sum of them means the drawing fails to accurately portray the lock when in use. For more details on the Navigation’s locks see this page.
The barges used on the navigation were about 70 feet long and 13 feet wide (21.3m x 4.0m) - not 20 metres long. Whilst shorter than most of the locks, they were only a little narrower than the masonry supporting the lock gates. Most of the locks were about 90 to 100 feet long between the bottom and top gates. Thus the barge shown should be larger than portrayed.
The drawing seems to show the water level within the lock chamber to be higher than the water in the summit level of the canal leading to Black Bridge on the right of the drawing (the sawmill was on the west side of the lock).
The representation of the lock gates is wrong:
The gates would have been mitred in the form of a shallow ‘V’ pointing upstream so that they were self-sealing from the pressure of the upsteam water. Two gates in a straight line as shown would not have been able to withstand the pressure of water as the difference in levels on either side was increased.
The gates opened back into recesses in the brickwork to protect them from barges entering or leaving the lock.
The gates would not have been hung from the lock masonry in the manner shown with the top pivot (hinge) landward of the brick side of the lock. If hung like this, how would the bottom of the gate be pivoted?
The balance beams used to open and shut the gates would have been more substantial than those shown.
No means of letting water into or out of the lock (paddles) have been shown.
Water appears to be emerging from under the top lock gates. The water used to fill / empty a lock entered / left using gravity. The water level to the right of the lock was higher than that below the bottom gates on the left.
A boat rising in the lock might have been controlled using ropes ashore to posts or bollards or by shafts from the lock side. The idea of a boatman (or even two) standing on the boat with a shaft would have been ineffectual and potentially life-threatening. The force of water entering the lock could be too great for a man to control the boat with a shaft whilst stood on it and he would be more likely to use a shaft stood more safely on the side of the lock.
The barge would not have been loaded with cargo piled some five or six feet higher than the gunwales - potentially the boat could capsize or some of the cargo slip down the heap and over the gunwales into the water. In addition, the barge would have had great difficulty passing under the low bridges on the Navigation.
The axis of the waterwheel was aligned approximately with the side of the mill - not outside it. The wheel was also substantially lower and wider than that shown - almost as wide as the curved brickwork. Some contemporary drawings indicate fendering in front of the wheel presumably to protect it from boats.
Water is shown emerging from under the waterwheel but it would have been stopped whenever a boat used the lock as the wheel could only operate when there was a head of water with the lock empty.
One of the pictures on this page is shown by kind permission of Marie Keates. A keen walker, she has written about and illustrated several attempts to walk the full length of the Navigation during 2013 in her blog at https://www.iwalkalone.co.uk. She has walked along all or parts of the Navigation often since then: all illustrated with some excellent photographs.