It is ilegal to drive on the footway and also to park on the verge. It should be reported to the police, although these days they tend to select which offences to take action on. Many officers do not like to deal with what they see as minor offences when they could be waiting for a major offence to turn up. If they do not take action, which should include telling you what they have done, you can complain to the officer in charge if you feel strongly enough. Bear in mind though, that the only evidence of the offence is what you have seen, so you would be required as a witness if the case goes to court.