<P> The motorway is 193 miles (311 km) long and was constructed in four phases . Most of the motorway was opened between 1959 and 1968 but the southern end was extended in 1977 and the northern end was extended in 1999 . It forms part of the unsigned European route E13 . </P> <P> There had been plans since before the Second World War for a motorway network in the United Kingdom . Lord Montagu formed a company to build a' motorway like road' from London to Birmingham in 1923; however it was a further 26 years before the Special Roads Act 1949 was passed which allowed for the construction of roads limited to specific vehicle classifications, and the 1950s when the country's first motorways were given the government go - ahead . </P> <P> The first section of motorway was the Preston Bypass in Lancashire, which opened in 1958 (now part of the M6 motorway). The M1 was Britain's first full - length motorway and opened in 1959 . The early M1 had no speed limits, no central reservation or crash barriers, and no lighting . </P> <P> The first section of the motorway opened between Junction 5 (Watford) and Junction 18 (Crick / Rugby) on 2 November 1959 together with the motorway's two spurs, the M10 (from Junction 7 to south of St Albans originally connecting to the A1) and the M45 (from Junction 17 to the A45 and Coventry). Parts of the Hertfordshire section were built using steam rollers . </P>

What was the speed limit on the m1 when it first opened