Leaf-slip is a problem in other countries
(See wikipedia) but it is particularly bad in Ireland and Britain because of the amount of rain we get around the time leaves are falling.
The delays are nowhere near as bad as they were a few years ago when Irish Rail were using locomotives on the Sligo line but when you have a single line railway where most trains have to cross with two others, knock-on delays are inevitable when you have poor traction.
The only real way to deal with it would be to provide more crossing points to mitigate knock-on delays or to run trains to clean off the leaves with high-pressure water or steam. One thing that would help at a relatively low cost would be to get the second platform at Enfield back in action so that it could be used as an unscheduled crossing-point.