What was the doctrine introduced in English law, serving as a defense to the principle of vicarious liability, and stating that an employer/master cannot be held liable for injuries caused by the negligence of a fellow servant?

The doctrine of common employment was introduced in the English law probably as a defence to the principle of vicarious liability. This doctrine stated that an employer/master cannot be held liable for the injuries of his/her servant caused by the negligence of a fellow servant. Various laws came into place in England trying to abolish the doctrine of common employment as it was considered to be against the safety and betterment of the employees. After working on lot of permutations and combinations the defence of common employment was abolished by the Law Reform (Personal Injuries) Act, 1948.