Boiler flue through roof - how to cut tile?

When they are, they just use one of these -

In article , Luke writes

Don't worry on the building regs, even if there was a requirement it's v unlikely that anyone would notice or care. Although for more noticeable and notifiable jobs I have done the obvious work on a Sunday when it's quiet and council bods[1] are at home with their feet up.

It's common practice to nail every fourth row, IE lay three full rows, nail the next row, but even then they only usually get one nail per tile - its not imperative with interlocking concrete roof tiles - they're only nailed every 4th row so that the wind cannot 'strip' the entire roof in the event of a storm

I was worried that the tile I wanted to remove would be nailed. However once I had removed the tile I learned that there weren't any nail holes in the tiles at all! To remove the tile I pushed up three tiles above the one I wanted to remove, to make a gap. This needed a bit of persuasion with a hammer which I braced against the tile using a piece of waste wood. Then I could simply lift the tile clear. It was quite awkward to "shuffle" the tiles back down again afterwards - as you can imagine there is quite a lot of friction to overcome, and you can't easily get a decent grip on the tile.

Luke