GrumpyGregry
Here for rides.
Whilst it is somewhat more complex than a simple efficiency ratio, and may require the interested donor to break out a calculator, all the data you need to compare UK charitable apples with other UK charitable apples is contained in their accounts and annual report. It's called SORP.I'd like to see a requirement for all registered charities to publish a number showing the actual percentage of their annual funds that goes directly to the cause they are supporting. I know many will argue that it's too simplistic, but it would make for interesting reading.
The knack is in avoiding comparing apples with pears.