A major limitation with the list is that it only includes comedians who have set up their own companies, which results in their finances being visible in the public domain. A lot of comedians, possibly the majority, don't do this. As might be expected, tax dodger comedian Jimmy Carr makes sure his finances are not visible in the public domain.
On the list I would only regard a few as being even mildly amusing. The two frontrunners, Peter Kay and Michael McIntyre, I don't find funny at all - their style seems to me to be a highly observational form of observational comedy, but to their credit they don't seem to do much political material, and I think Kay has never appeared on a comedy panel show. The least funny comedian in the UK (in my opinion) is the man at 19th on the list, Marcus Brigstocke, whose act consists almost entirely of political material. Brigstocke was once described by a radio critic (ironically working for the left wing magazine New Statesman) as being "the unfunniest àrse in the universe".
Another thing you can pick up from that list is that the comedy panel shows are a bit misleading - many people watching these shows might think that comedians like Frankie Boyle, Sean Lock, Jason Manford and Sarah Millican are representative of the hoi polloi, whereas they are actually millionaires.