The Earl of Sandwich probably played whist not bridge but that is not important. The bid comes from one’s suits being sandwiched by opponents’ suits. I mentioned Sandwich No-trump because it should be in everyone’s bidding repertoire. Unless previously discussed, it will probably confuse partner. However, it provides a valuable lesson. If both opponents are in the bidding, one does not want to use one no-trump to show a strong hand. Partner will be bust and all you have done is warned opponents not to go too high. The declarer will know how to take the finesses.
That is why one no-trump overcall when both opponents have bid shows a two-suited hand and usually less than opening points. It is best to play a hand with points evenly distributed between dummy and hand for communication (entries). With a strong hand, one has to hope either that partner has the shape to do something or that the opponents bid too high getting themselves into trouble.
The bidding: East opens the bidding with 13 points and West bids a heart. North with five spades and six diamonds and less than ten points bids one notrump. West doubles four spades because he thinks five hearts will not make.
The contract: Four spades by South doubled
The opening lead: The king of hearts
The play: South ruffs the opening lead and takes the trump finesse. With an eleven-card fit, one plays for the drop, but with a ten-card fit, a finesse is used.
Trump is drawn and the diamond finesse is taken. It works and 13 tricks are claimed. Penalty doubles are risky when a five-five distribution is afoot. So five spades making six undoubled is the best East and West can do, unless they are left in four hearts which is unlikely.
The result: Four spades doubled making seven for +1390.