The Warwick and Birmingham Canal Company obtained an Act of Parliament in March 1793, which authorised the construction of a canal from the Digbeth Branch Canal of the Birmingham Canal Navigations to Warwick, where it would end at Saltisford Wharf. The plans showed three tunnels, at Shrewley, Rowington and Yardley, but as construction progressed, the last two became deep cuttings. This was not an option at Shrewley, as the route passed under the village. The plans also specified that the tunnel would be suitable for boats but not barges, implying that it would have been suitable for narrow boats, common on the Birminghamsystem, but not for wider craft. However, construction of the Grand Junction Canal, which would provide a link to London, was started at a similar time, and the committee wisely took the decision in April 1794 to increase the width of the tunnel to, allowing wide barges to pass through it. The width of the bridge holes was similarly increased to in May. The tunnel is long, built of brick and is wide enough for two narrow boats to pass each other, although it has no towpath inside. It officially opened on 19 December 1799 when the rest of the Warwick and Birmingham Canal was completed, although no trading took place until the following March. It became part of the Grand Union Canal in 1929 following the amalgamation of the canal company with several others, including the Grand Junction. There are actually two tunnels: at the northern portal, the towpath splits off and rises on a ramp and then enters a tunnel of its own, until it reaches the road which crosses the tunnel; having crossed this the path then descends on another ramp to reach the southern portal. The interior of the tunnel is unusually wet and this has led to the creation of flowstone formations.
Location
The tunnel runs from the south-east to the north-west. From the northern portal, the canal is level for to the bottom of a flight of five locks at Knowle, which raise the level of the canal by. Kingswood Junction, which connects to the Stratford-upon-Avon Canal occurs about halfway along this stretch. To the south, the canal is level for around to Hatton Top Lock, the first of a flight of 21 locks which drop the level by to reach Warwick.
