The A2020 is a previous road in Kent

Kent

Kent is a county in southeast England, and is one of the home counties. It borders East Sussex, Surrey and Greater London and has a defined boundary with Essex in the middle of the Thames Estuary. The ceremonial county boundaries of Kent include the shire county of Kent and the unitary borough of...

 but has been renumbered to A20 following the construction of the M20 motorway

M20 motorway

The M20 is a motorway in Kent, England. It runs from the M25 motorway to Folkestone, providing a link to the Channel Tunnel and the ports at Dover. It is long...

.

Between 1960 and 1961, two sections of (what is now known as) the M20 motorway were built between junctions 5 and 8. This was known as the Maidstone Bypass and was renumbered the A20(M) as it bypassed the stretch of the A20 through Maidstone

Maidstone

Maidstone is the county town of Kent, England, south-east of London. The River Medway runs through the centre of the town linking Maidstone to Rochester and the Thames Estuary. Historically, the river was a source and route for much of the town's trade. Maidstone was the centre of the agricultural...

. The A20 road was then renumbered as the A2020, which is the source of the name of the 20/20 Business Park, situated close to junction 5 of the present M20.

However, during 1971 and later in 1977, the A20(M) was extended westwards towards London, England and was renamed the M20 motorway, and as a result the A2020 reverted to being the A20. The 20/20 Business Park has kept its name, however.