The Scott Trust established its editorial line as "liberal" (in the UK, not the US sense) and it's generally hewed to that. Despite occasional flashes of appearing radical it's an establishment, social liberal paper that believes in slow reform.
I also wish it were more of a leftist paper but it is what it is.
it's sad but I would imagine that it probably wouldn't exist as it does today if it genuinely rocked the boat. at some point--probably in the 70s and 80s when the establishment was really reasserting itself--there would have been some kind of hostile takeover or other method of silencing it. maybe that did happen in fact, I do not know