Can I carry passengers?
Mobility vehicles designed to carry two people cannot be used on the pavement or road because they don't meet the definition of an invalid carriage in law. With regard to children, the law does not explicitly state that an adult carrying an infant in a sling/pouch is unlawful. However, it is not permitted to carry anyone else on a mobility vehicle e.g. children standing on the vehicle etc.
Taken from a police website.https://www.askthe.police.uk/content/Q805.htm