No the B class was the development class. Tornados were a one design. Not to be confused with a single manufacturer one design.
Tornado was one-design but with some freedom on sails, equipment, layout of equipment etc. As building methods went from plywood to sandwich and the introduction of tighter production control procedures the class rules were tightened up to reflect this.
The last version of the class rules were very much one-design on the aspects that matters but with freedom to lay out control systems etc as you like.
