Iron Hart
It’s For the Birds

The Unlocked Canal

Stoke Hammond lockThis is Stoke Hammond lock. As in five other places on the canal the lock was right up against the bridge, so the bridge had to be rebuilt with a second arch. This is the South side of the bridge, and the furthest arch now takes the farm track over route 6 of the National Cycle Network.

In the 1830s the Grand Junction Canal company found stiff competition from the new railways in England.

In response they reduced their tolls and soon there was a great increase in the number of boats on the canal. But every lock became a bottleneck, so they twinned the locks; building a second lock next to nearly every existing one.

All the locks through North Bucks were twinned, except for the one at Fenny Stratford, perhaps because it has such a small rise. The work finished in mid 1839.

Bridges very close to existing locks had to be modified with a second arch, and there’s several in North Bucks.

These twinned locks sped up the single narrow boats that made up most of the canal traffic, and there was a saving in water, which always makes its way to the lowest point of the canal.

In North Bucks that’s the stretch between Fenny Stratford and the Iron Trunk aqueduct at Old Wolverton. The canal is now known as the Grand Union.


I referred to this comprehensive history of the canal in the writing of today's post.

But pumping stations were being built at around the same time at every lock, and together with a trend towards pairs of boats rather than singles, the need for the twinned locks dissappeared. After a while they began to be filled in.

There is very little left of these second locks, but there is plenty of evidence to show where they once were. Here is what’s left of some of them.

Site of second lock at SlaptonAt Three Locks, the canal has been stopped and drained for repair work. The short square ended piece of canal nearest the camera was the approach to the twinned lock; all three locks were twinned. I think this grating in the middle of the photo usually lies across the blocked off end; some water seems to flow through there.

Drained pound at Three LocksAt Three Locks, the twinned lock would have been in the sun lit area to the right of the existing lock, the middle of the three. I think the pairs of locks were offset to allow clearance to swing the lock gates; the removed lock further away from the camera. On the right of the picture is a collapsed canal bank. This photo is from the South.

Blocked off arch  Grove in BucksAt Grove lock, the second arch is walled off. On the other side of the bridge the wall is underground, and over the top of it there’s a ramped access down to the side of the remaining lock. A large pipe in the blocked up arch had water coming out of it constantly when I visited. This is the North side of the bridge.

Site of second lock at SlaptonAt Slapton lock it’s a similar arrangement to Stoke Hammond, but the removed lock was on the other side of the canal. From the local layout I suspect the removed lock was the second one to be placed here, but it’s hard to be sure. Viewed from the South, this is another farm bridge.

Double arched canal bridge  SlaptonSlapton lock from the North. Whatever remains of the removed lock is underground, through the right hand arch. Which side a lock was added would depend on what was easiest at that particular location, and the same would apply to which lock was later removed. Note that the right hand arch doesn’t quite match the left one.

I use Pentax cameras for many of the photos on the North Bucks Wanderer.

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