Greg, I would bet that Maggie learned that hymn at school just as I did in primary school over a half century ago, grew to love it as it was, RVW version and all. It was YEARS later before I found its true origins: I can appreciate it now in ALL of its versions. (This is not to say that I'm a Thatcherite, far from it, but I'd defend her right to choose, whatever extra meanings anyone wants to attach to it).
I liked her choice of music generally, especially the Welsh tune (Hyfrydol)for "Love Divine", which we also sang at school and had at our wedding, but is now lesser known, and LD is usually sung to a very boring plonky tune by John Stainer (oh dear, did I really say that?)
And I could quote other examples of songs that are frowned upon by purists as they were not the originals, and in some cases became better known than the originals.