There lies a distinction between non-service of notice and a notice though served but with some kind of procedural irregularities in serving. In the case of former category of cases, all consequential action, if taken would be rendered bad in law once the fact of non-service is proved whereas in the case of latter category of cases, the consequential action, if taken would be sustained. It is for the reason that in case of former, since the notice was not served on the person concerned he was completely unaware of the proceedings which were held behind his back thereby rendering the action “illegal” whereas in the case of latter he was otherwise aware of the proceedings having received the notice though with procedural irregularity committed in making of such notice on him. If a person has a knowledge of the action proposed in the notice, then the action taken thereon cannot be held as being bad in law by finding fault in the manner of effecting service unless he is able to show substantial prejudice caused to him due to procedural lapse in making service on him. It, however, depends upon individual case to case to find out the nature of procedural lapse complained of and the resultant prejudice caused. Prabin Ram Phukan v. State of Assam, (2015) 3 SCC 605.