Great Western Railway Co v Mostyn (Owners),  AC 57 per Lord Dunedin:
… if from the opinions delivered it is clear - as is the case in most instances - what the ratio decidendi was which led to the judgment, then that ratio decidendi is also binding. But, if it is not clear, then I do not think it is part of the tribunal’s duty to spell out with great difficulty a ratio decidendi in order to be bound by it.
Scruttons Ltd v Midland Silicones Ltd  AC 446 per Lord Reid:
I would certainly not lightly disregard or depart from any ratio decidendi of this House. But there are at least three classes of case where I think we are entitled to question or limit it: first, where it is obscure, secondly, where the decision itself is out of line with other authorities or established principles, and thirdly, where it is much wider than was necessary for the decision so that it becomes a question of how far it is proper to distinguish the earlier decision. The first two of these grounds appear to me to apply to the present case.
F.A. & A.B. Ltd v Lupton  AC 634 per Lord Simon of Glaisdale at 658:
… what constitutes binding precedent is the ratio decidendi of a case – that is, generally, those facts which the tribunal whose decision is in question itself holds, expressly or impliedly, to be material.