These historical maps are by the late Dr. Mike Stevens
In 1845 the Ellesmere & Chester Canal Company took over the Birmingham & Liverpool Junction, and some railway companies to form the Shropshire Union Railways & Canals Company. Later they also bought the Shrewsbury Canal and both parts of the Montgomery Canal and leased the Shropshire Canal. The original idea was to build more railways, and convert much of the canal mileage into railways as well. But they were then taken over by the London and North Western Railway, who saw it as being in their interest to keep the canals running so as to provide them with feeder lines reaching deep into territory controlled by their rivals, the Great Western Railway.
This was but one case of canals falling into railway ownership, which became prevalent in this decade and was to continue into the future. Even the great Trent & Mersey and the Birmingham Canal Navigations succumbed in 1846 although, unlike some, they both thrived under their new ownership, the latter continuing to build new lines.
The Hereford and Gloucester Canal had been proposed in 1774, started around 1791. By 1798 it had reached Ledbury (from Gloucester) and stopped there having spent all its money. A fresh burst of enthusiast from 1830 brought in more capital, and the canal finally reached Hereford in 1845.
The Charnwood Forest line of the Leicester Navigation had never been completed, as the enthusiasm for it on the part of the coal-owners it was planned to serve had waxed and waned. Part of it had been built as a canal and part as a tram-road. But the coal-owners finally decided that the Ashby Canal would serve them better, so the Forest line fell into disuse and was finally abandoned in 1848.
By the end of the decade, the Hertford Union Canal was closed, following the bankruptcy of its proprietor, Sir George Duckett.
The Oakham Canal also closed. While most other canals continued to function, their profits were suffering badly. This was particularly true of the rural canals, such as the Thames & Severn, whose main trade had always been local. Some of these had a short burst of prosperity for a few years while they were carrying the materials to build the railways that would eventually put them out of business.
See also an Original 1850 map of the waterways of England and Wales (external link) by Joseph Archer in Dugdales "England and Wales Delineated",