He said before he died at age 85 in February that he wanted the sign to serve as a warning to young people about the dangers of tobacco smoking.
The sign was designed to look like the health warning on a packet of cigarettes.
The printed placard at his grave will be left in place for a week.
The hearse carrying his body through the town of Dover 100 miles (160 kilometers) southeast of London had several of the printed signs displayed in the windows.
