Thanks for the comments, Ken.
The possibility that Rachel was the intended victim is interesting, and an angle not previously suggested. As with all the theories in this case there are frustrating points for and against. How physically similar Rachel and Liz were, we simply don't know. If they were very similar that could give substance to the suggestion. What we do know is that on the night of the murder there was a waxing moon, which would have given some light, but whether it was enough to see the person clearly is debatable. However, if the attacker was one of Ramsden's circle, he would have known both girls very well and unless the attack was carried out in a panic, I think he would have known who the girl was, even in poor light. Given Liz and Rachel's colourful love lives, it's certainly likely that both had made enemies. Rachel, in particular, had very likely made an enemy of Anne Ramsden, Thomas's wife, but the way the act was carried out seems unlikely for a woman.. If the murderer was Thomas or one of his apprentices, I think they would have been aware of Rachel's whereabouts, due to her being the Ramsdens' servant. On the night in question she was doing the Ramsden's family's laundry until around 10.00 and when she left, was accompanied by one of Thomas's brothers and one of his sons and I suspect this accompanying her home was a regular occurrence. As a result, I think it unlikely the attackers would have thought the girl hurrying alone down Sheepcote Lane was Rachel. Of course, it isn't outside the realms of possibility either...Frustrating, isn't it!