Since bridge experts are human (despite a formidable weight of opinion to the contrary), if they were granted just one wish they would probably ask for more than their share of aces and kings. But if that wish were barred I think they might pray always to make the best opening lead.
It would be (close to) an ideal choice. Consider the case of the Italian team which has won the world championship three years in a row. Expert American observers have long been impressed by the Italians' high percentage of hits in the opening-lead department. I don't contend, of course, that three successive championships have depended exclusively on opening leads, but this was unquestionably a big factor.
It is always something of a comfort when partner of the opening leader has bid a suit. This at least provides a peg for the leader to hang his hat on. Yet it is by no means clear-cut that one must always lead the suit partner has bid. In the current offering West made a wise decision.
Before we get around to the opening lead, let's notice that West had a decision to make in the bidding, too. With his partner going it alone up to the four level, vulnerable against nonvulnerable opponents, there was some temptation for West to bid five diamonds, either for a possible make or for a sacrifice, but the unattractive distribution of his hand naturally militated against drastic action.
We are not unaware that had West chosen to bid five diamonds that contract might well have come safely home to roost. It would have required a club lead from South to break the contract, and there was a distinct likelihood that that opening would not have been forthcoming. Against a red-suit attack East would draw trumps and lead the spade jack. South would win, and would no doubt shift to clubs—but too late. East wins, crosses to dummy with a trump and takes another spade finesse. When the queen falls, one of dummy's clubs goes off on East's fourth spade. If South's initial lead is a spade, East has this job done for him before he loses control in clubs.
But let's get back to things as they were, with South the declarer at four hearts and West on lead.
West had sound reasons for refusing to open partner's suit. East's unassisted drive to the four level marked him with considerable length in diamonds. West's holding of four cards convinced him that there would be few if any defensive tricks in that suit.
Also, West knew that there was no need to establish diamonds, for if a diamond trick was available it could be cashed at will. He knew that he was not going to 'have many chances to lead, so it behooved him to take advantage of his one sure chance, the opening lead.
He therefore led the jack of spades, with an effect which was very salubrious for the defenders. Declarer ducked in dummy, and East played the encouraging seven spot. South won, drew trumps and knocked out the ace of clubs, but East now exploited his partner's good opening lead by underleading the diamond ace to put West in. A second spade play through dummy's queen now gave East-West the setting trick.
Playing at a suit contract, if you have only one or two cards in the suit which has been mentioned by partner, then it would appear that your choice of opening leads has been made for you. But where you have great length in his suit, a search for a more constructive lead should recommend itself to you.