Unfortunately it is not possible to complete the whole of the South Downs Way by horse and carriage as it is predominantly a Bridleway.
Legally you are only allowed to take a horse and carriage on Byways, Restricted Byways and Public Roads. The South Downs Way does follow a number of Public Road sections in Hampshire, quite a long section of Restricted Byway in Hampshire and West Sussex and a short section of Restricted Byway in East Sussex.
However, some of these Byways and Restricted Byways also have Traffic Regulation Orders placed on them to try and prevent illegal use and abuse by motor vehicles. Sadly, because of this, it has meant also closing some of it off from horse and carriage.
The South Downs Way team do not manage or impose Traffic Regulation Orders (TRO), they are controlled by the local Highway Authorities (individual County Councils).
For further and more detailed information relating to Traffic Regulation Orders and where you can go with a horse and carriage we would advise contacting the local County Councilís Rights of Way teams.
The South Downs Way team hope to be able to provide more advice and suggestions for routes for Carrige Drivers which include the South Downs Way in the future.