If you want to give to, say, cancer and want to find a good charity in that, how can you currently find out which org is any good? Essentially you can’t: charity ‘due diligence’ is way too hard for almost any non-professional donor.
It matters since most £s given are given by ‘normal people’ (for whom philanthropy isn’t a job) and those people are the majority of donors. The pattern is the same in most developed countries. Those donors really don’t have much option but to give randomly or based on hear-say. 

We’ve thought long about fixing this, and are now moving to action. Our ‘strategy’ is to borrow other people’s homework: create & market a website which compiles the recommendations of (charities funded by) sensible grant-makers, & of independent analysts.
A brief paper outlining the concept is here. It’s very early days but you’ll get the drift. We’re very interested in your views: please send them to admin [at] giving-evidence [dot] com