Determination of the vexed questions as to whether a contract is a contract of service or contract for service and whether the employees concerned are employees of the contractors has never been an easy task. No decision of this Court has laid down any hard-and-fast rule nor is it possible to do so. The question in each case has to be answered having regard to the fact involved therein. No single test – be it control test, be it organisation or any other test – has been held to be the determinative factor for determining the jural relationship of employer and employee