It looks to me like Equality Trust put a fair amount of thought and research into their website, did their best to paint a picture of what's going on in the UK by using multiple reputable sources, and tried to explain why that picture is dire, not just for those with a net worth that rounds to £0 but for the nation at large, with several dozen citations to back that up.

Thank God we have this one number from some Credit Suisse marketing material to invalidate all of that.