Hi Richard, in my experience the simple answer is "probably". Breaking your journey (effectively that's what you are doing) is permitted on anything other than Advance tickets. However, since you would be changing trains in Edinborough anyway, no one will know that you haven't just got off a train from Strathcarron - since it is not a straight-through train from Strathcarron to Leeds. If that makes sense...

You could also post on the Challenge Facebook group, if you use that, as it's a lot more active than this message board these days.

Regards, Adrian