January 24 2008 in his The London Times bridge column, Andrew Robson published one of his articles from his renowned series: Most common defence mistakes. He begun the article with this words…
I dont like the adage: “Never underlead an ace”…But do not misunderstand me … Underleading an Ace is dangerous and should be avoided at all costs at trick one defending a suit contract … But it doesent work in a NT contract where leading an ace from a 5th cards suit with the A…can give a cheap trick but is a future investment …it will produce lots of tricks…
The saying isnt true in suit contracts after the dummy is over the table…
Yesterday October 15 2012 
in the 2012 Monaco Cavendish an example of this situation appeared in one of the tables that reaffirmed what Andrew Robson wrote and that is since always a part of the popular tradition of bridge. Team Angelini faced team Welland: Piekarek in East opened one heart, South and his partner passed and Benito Garozzo didnt reopened. Declarer made 8 tricks scoring +110.
In the other room West – East were Alfredo Versace playing with his sponsor Angelini.
Angelini opened 1
strong y Versace showed weakness with his 1
. Angelini continued showing his heart suit and Versace, perhaps a little optimistic because of his Qxx in hearts redeclared 1
. Now Angelini with K Q x said 2 and they landed in 4.
Sabine Auken, the leader decided to break the rule and lead the 4.
Versace played dummy’s 9, Welland in South with K 10 8 2…played his 10…Versace won the trick with his J. What a punishment for the defence, because in this way the declarer got an additional entry to his hand, to play the trump suit.
In trick number two Alfredo played a trump to the dummy and won the trick with the K, now he could return to his hand to his 
Q to repeat another trump. THE END. Declarer made his 10 tricks scored +420 and added 11 IMPs for his team.