It's really made me reflect on why mainstream didn't work for DS - specifically the 'not engaged' part.
(We're not in Scotland but still highly relevant).
He was on a P/T timetable for 2 years - he kept up academically but that was due to his innate cognitive ability.
One example I can think of was a school trip (that I had to go on too) which was based on something the rest of the class had done a topic on, but he hadn't been there.
No one in his class thought in advance that it would be a good idea to include him in that topic.
Not his teacher, not his full time 1:1 TA.
No one told me about the topic so I didn't know to do anything about it at home.
So we went on the trip and DS was totally disengaged, he didn't have any background info to make it interesting to him.
He banged on a table when he was bored - the person running the trip (not from the school) told him off - clearly had not been briefed DS was autistic, so then DS hid under a table for the rest of the trip.
Sorry to rant on but this is just one example of why inclusion never worked for DS - because it wasn't inclusion! 
He was always an afterthought, a bolt on.
Now he's at a SS where he's at the heart of all the planning and so far (early days) he's flourishing.
Ok! Rant over. Shall get on with my day!