Three weeks after service of the writ in an action on a building contract, after appearance had been entered and further particulars of the statement of claim indorsed on the writ had been asked for and delivered, the defendant’s solicitors learned for the first time that the contract contained an arbitration clause. The defendant immediately gave notice that he desired the matters in dispute referred to arbitration. On a summons by the defendant to stay proceedings in the action, under sec. 5 of the Arbitration Act 1928—