Assuming this is a caravan and motor home, it must be attached to the towing vehicle and show the number plates and so on to be on the public highway.
There is a specific offence relating to the parking of a trailer/caravan in the street and that is under Regulation 103 of the Road Vehicles (Construction and Use) Regulations 1986, which is solely a Police matter. As a result, unless there is absolute proof of wilful obstruction all enquiries in relation to caravans or trailers parked in the street should be addressed to the Police.
To park any vehicle on the grass verge or footpath is regarded as wilful obstruction of the highway and as such enforcement action can be taken under the Highways Act.