They do food really, really well. Everyone likes M&S food, and they rarely seem to put a foot wrong with it. I think they either need to just do that, or else get a seriously radicalizing team in for clothes. Just copy John Lewis ffs - how hard can it be? 
My children are long past the children's clothing stage, but even when they were little I rarely bought clothes in there - horrible tacky crap. And even their school uniforms became bizarre - if I wanted a pinafore without a revolting huge metal flower on the zipper, or a plain gingham summer dress without stupid flounces, I ordered it from JL even then!
WHY DON'T YOU LISTEN, M&S???