A four-needle system was installed between Euston and Camden Town in London on a rail line being constructed by Robert Stephenson between London and Birmingham. This was a similar application to the Liverpool project.The carriages were detached at Camden Town and travelled under gravity into Euston.The change was motivated by the economic need to reduce the number of telegraph wires used, which was related to the number of needles.
However, the cables soon began to fail as a result of deteriorating insulation and were replaced with uninsulated wires on poles.
From this point the use of the electric telegraph started to grow on the new railways being built from London.
All that was required were a few simple signals such as an indication to the engine house to start hauling.
Cooke was requested to build a simpler version with fewer codes, which he did by the end of April 1837.
Their differences were taken to arbitration with Marc Isambard Brunel acting for Cooke and John Frederic Daniell acting for Wheatstone.
Cooke eventually bought out Wheatstone's interest in exchange for royalties.
The telegraph arose from a collaboration between William Fothergill Cooke and Charles Wheatstone, best known to schoolchildren from the eponymous Wheatstone bridge.
This was not a happy collaboration due to the differing objectives of the two men.
In May 1837 Cooke and Wheatstone patented a telegraph system which used a number of needles on a board that could be moved to point to letters of the alphabet.
The patent recommended a five-needle system, but any number of needles could be used depending on the number of characters it was required to code.
A system was needed to signal to an engine house at Camden Town to start hauling the carriages back up the incline to the waiting locomotive.