The Highways Agency is already running a consultation on a 32-mile section of the M1 in a move to cut air pollution and has now launched a similar consultation on a 2.8-mile section of the M3.

The new limit would apply between junctions 3 and 4 from 7am to 7pm, seven days a weekend and, according to the agency, will actually reduce journey times during peak hours.

The planned limit would likely be removed by 2019, as cars become less polluting.

The RAC, which has already expressed its concerns over the M1 limit, re-emphasised its message that this could be the thin end of the wedge

RAC technical director David Bizley said: ‘Given the landmark announcement in early January about a reduced speed limit of 60mph on a 32-mile stretch of the M1 in order to protect air quality in the area, this should really not come as a surprise.

‘It does, however, come hot on the heels of the first announcement and invites the question as to whether any of the eight other planned all-lane running, smart motorway schemes which the government have heavily invested in will also need to have reduced speed limits put in place to protect air quality?

‘News that the restriction should lead to higher average traffic speeds on this stretch is something of a consolation for commuters, but others who travel outside of peak times will no doubt wonder why they can't drive at 70mph on a clear motorway.’

The M3 consultation runs until 11th April while the M1 one ends on 3rd March.