Would it not have been better to bid seven clubs, as he considered doing?
But four hearts was passed around to South, who bid five clubs.
So he bid two clubs, which in theory indicated three cards but was the least evil.
But North made a disastrous decision by bidding five clubs.
The normal action was to bid two clubs, a fourth-suit waiting move.
East, though, tried for game by bidding four clubs, pushing his side one level too high.
This gave West a chance to open one club, and he eventually bid four clubs over three hearts.
What would have happened if West had bid five clubs?
He bid three clubs, which was an attempt to suggest a lead rather than a serious move toward a club contract.
A few would bid three clubs, although that suggests a stronger hand.