Do Leylandii leaves compost down to leafmould?

I don't have any leylandii myself of course, perish the thought! But I do have a next-door-neighbour with a row of leylandii, and they poke their branches over our boundary line. I'm not too worried about it, as they're only over my hardstanding at the front, and last year, just after I moved in, the neighbours were sweet enough to ask permission to come onto my property and give them a wopping great haircut - they cut about six feet off the height, and pulled them back to the boundary limit. They even took away all the branches and clippings.

But last month, a year later, they were peeking over the fence again ... and I was wondering about them being a soource of humus and soil feed for the blueberries, when I ever get around to planting them. I know pine needles are good for that, but do leylandii leaves count as pine needles?

The other reason I want to cut them back a bit is that they shade my living room when they get too big, and that room needs all the help it can get.

So an experiment was called for: I've been cutting some of them back a bit, to the boundary, and bagging them, then asking friends and online resources about this. And I have an answer!

Turns out they take a minimum of 3 years to compost down .... thats not really good enough, much too slow a turnover, and much too boring (and nonproductive) use of my property. So I've reached a compromise - give them a haircut once a year, because it *is* the front of my property, and it doesn't look nice, and put the clippings directly onto the ground on the blueberry-patch-to-be. They *are* acid enough to act as pine needles. I'm going to have the happiest blueberries in the south of England!