"Nor does being in favour of an expanded grammar school model mean that someone doesn't care about the least able."
It does if there is evidence (there is) that the expansion of the grammar school model would result in poorer outcomes for the majority of children who are not selected, and you are still advocating for it!
Re: the issue of FSM and the work of the Sutton Trust, I come from an area with high levels of deprivation and large numbers of new immigrants. The very tiny number of dc's at my dc's inner city primary who got into a grammar (super selective) came from one of two backgrounds: they were from hard up by highly intelligent and super motivated new immigrant families, and from very ambitious professional m/c families. All the children were tutored by parents and had paid for tutoring from very early on.
In short, the very successful FSM children in the UK who are gaining entrance to grammars are overwhelmingly coming from ethnic backgrounds and most have highly educated parents, regardless of family income. Two grammars in one part of London have an intake of over 50% Asian children in an area where they make up only 13% of the primary school intake.
The children who are hugely, massively under represented in grammar school intake are poor white children, and poor Caribbean children, who are as rare as hens teeth in grammars.
The push to increase the numbers of children from poor families in grammar is massively wrongheaded because it will always and forever only ever pick up those children who are already succeeding highly because of massive parental input, and these children are already thriving in the non-selective state sector. It can never address the real issue the UK system has with helping poor children achieve their potential which is all about the children who are currently failing in education because of cultural issues and a lack of parental input.