Richard III lost in Leicester

Richard was buried in the Greyfriars in Leicester, this was demolished, but it was known that his remains were buried in Robert Herrick's garden in the early 17th century, but it beggars belief that his grave should be forgotten and ended up under a socials services car park.

Whatever people think of Richard and there are many different views, but he was someone of ability and personal courage. Can anyone explain how the Leicester authorities and antiquarians allowed this?