Where might petrol be leaking?
but I can't be bothered any more to tinker with the little **** any longer than necessary)
Those are mutually exclusive statements. You cannot find the leak unless you invest the time to look for it.
Clean/wash the engine and allow it to dry. Once dry, start the engine and while it is idling, look under the bonnet for leaks at the carbs. If nothing is leaking there, follow the fuel lines back until you find the source of the leak. If you do not find the leak with the engine idling, turn the engine off and continue to watch for the leak. Let us know what you observe.
It could be a leaky set of rubber hoses, a worn out float valve, an out of adjustment float valve, a leak in an inline fuel filter, a leak at the pump.... The list can go on. That's why you have to spend the time looking for the source.