An "Estimate of Expense" for the "London and Brighton Motor Way" dated 1905 amounted to £1,605,650 for a length of 40 miles, 1 furlong and 1 chain. It must be assumed that it refers to a very different kind of motorway from those we see today.
In the 1960s, when Governments drew up their programme for the completion of the first 1000 miles of motorway during the 1970s, the M23 was included. It was intended to link London with Gatwick Airport, Crawley and the Sussex coast around Brighton. It would also relieve pressure on the A23 and the towns and villages through which the road passed. The line of the motorway between Pease Pottage in West Sussex and Mitcham in the London Borough of Merton was fixed in 1968. The length between Pease Pottage and Hooley was constructed and opened in 1974.
However, to the North of Mitcham, where it was planned that the motorway would eventually link into the GLC’s Ringway 2, there were a considerable number of objections and representations to the effect that the Northern terminal of the motorway could not be considered in isolation from Ringway 2. This section of M23 was therefore put on hold pending further consideration. The GLC’sdecision not to proceed with the proposed orbital roads was the final nail in the coffin of M23 North of Hooley. The motorway could not just be allowed to terminate without having some way of dealing with and distributing the traffic from it. A group set up to consider the options and consequences of dropping this section of motorway. Suffice to say, and to the consternation of business interests in South London, M23 merely merges with A23 at Hooley and traffic crawls into London from there. It was presumably at this time that it was decided that there was no longer a case for continuing the motorway to the South of Pease Pottage. An extensive programme of improvements to the existing A23, from the Southern end of the M23, to the point where it meets the Brighton By-pass was carried out.
R Travers Morgan & Partners, as their firm was then known, designed and supervised the work as consultants to the RCU. They encountered a number of engineering problems particularly in relation to ground conditions, including the presence of underground mine workings previously used in the extraction of Hearthstone - not something one would necessarily associate with the South of England.
Included in the Hooley to Pease Pottage section of M23 is one of the few 4-level motorway to motorway junctions where it connects with M25. The original design included 7 bridges with steel box girders with spans up to 180 feet. The tender period was an unusually long one of 6 months, probably on account of the modifications being made to steel box girder design following the work of the Merrison Committee. The contractor - WC French - decided to use the time to redesign all except the top level bridge as prestressed concrete boxes. Their reasons were that they saw economies and the avoidance of possible complications with the steel boxes. It is not known if there were any contractual complications nor is there anything to say whether his assumptions about economies and potential problems were borne out.
The Gatwick Link was built to coincide with the southern section of the motorway.
An interesting analysis of the proposed extension into London, and it eventual abandonment can be found on this website page.
