Lavenham is a quaint 15th century town in Suffolk, England, with half-timbered houses and several restaurants and pubs with cold beer worth a visit. For centuries, there was only one road passing through. This became the High Street later. After the settlement bulked out a little, they built Lady Street around the back.
This was likely a narrow lane for petticoated ladies, who did not like being splashed with muck from horse-drawn carriage wheels. We suspect the council put up the sign when it became concerned about vibrations damaging buildings. This was after heavy-duty vehicles began using the narrow road to bypass gridlocks in the town.