Walsh

Advantages of Walsh
 
* Over a 1D response to a 1C opening, skipping the major suits and rebidding 1NT helps the bidding in the
    following ways:
 
   - When there are not enough points to play a game, it gives the partnership a chance to play an optimal 1NT, 2C        or 2D contract. 
   - When the partnership has enough points to play a game and the Responder doesn’t have a four-card major, 3NT
      can be bid without using any conventions.
   - When the partnership has enough points to play a game and the Responder has five diamonds and a four-card
      major, reaching the correct 3NT, 4M or 5D contract is not a problem.
 
* Since rebidding 1M promises five clubs and a four-card major, it is easier to compete, bid a game or bid a slam      with a 5-3 club fit.
* It is possible to penalize opponents with a surprise distribution if opponents balance the 1NT rebid.
* Most importantly, it is very difficult for the defense to lead and defend against no-trump contracts after the 1NT
    rebid; this is the biggest advantage of the Walsh convention.