Under the Clean Neighbourhoods and Environment Act 2005 (part two), it's an offence to park vehicles on the street in order to sell them and to park vehicles on the street in order to carry out repairs for a business. Section three states that it's an offence for a person to park vehicles on a street in order to be sold. There must be two or more vehicles on the same street, no more than 500 metres apart, acting as part of a business for the offence to be committed. He also needs them to be on trade plates: www.nfda-uk.co.uk/press-room/newsletter/2019/7/dvl...m

You can also report untaxed vehicles. Trade vehicles don't require taxing, but it is our understanding that if he hasn't got them on trade plates then they need to be taxed.