As it happens, my cat now rarely ventures out - probably as a result of territorial disputes and his inability to defend his territory as he ages!

I suspect fox culls will not be effective unless operated on a continuing basis because of the huge reproductive ability of foxes. In the countryside they are not fed and are shot by farmers because they are hugely destructive (my brother in law keep free range chickens ...) so the populations stays relatively low. But in the city, any gap created by culling will be rapidly filled by the cubs that don't die of starvation - which must be the fate of the majority.