|To:||Maidenhead Thicket (SU856807)|
|Length:||6 miles (9.7 km)|
|Now part of:||M4, A404(M)|
|Route outline (key)|
The Maidenhead bypass, which was originally allocated the number A4(M), was the first major section of the M4 to be opened in 1962, and the second overall with the Chiswick Flyover opening in 1959 as A4. In 1971, the M4 was redirected to a new alignment and the stub became the A423(M) (now A404(M)), whilst a section of the motorway was abandoned.
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