We spoke to the DVSA's Vehicle Testing and Roadworthiness team. They said, 'The historic exemption will apply to motorcaravans built more than 40 years ago where no substantial changes have been made to the vehicle in the last 30 years.' Different rules apply if the vehicle has been converted to a ‘living van'. There's more information on historic vehicles and the 40-year MoT exemption rule here: www.gov.uk/historic-vehicles

Information on exemptions and historic vehicles - www.gov.uk/government/publications/historic-classi...a