Ashcroft, 54, was recorded driving 8mph over the 40mph limit on the M4 in Brentford, west London, on 19 February last year.
He pleaded guilty to the single count of speeding at Lavender Hill Magistrates’ Court, though he did not attend the hearing.
The musician already had nine points on his licence from three previous speeding offences, leading to the six-month ban.
District Judge Daniel Benjamin stated Ashcroft had put other road users at 'risk of harm' and committed the offence 'without any intention of abiding by the speed limit'.