AS luck would have it, our roof sprung a leak a few weeks ago. A panicked run up the roof suggests it's the flashing - the bottomost strip - which runs up the roof along the chimney. For now, a heavy duty plastic sheet has been fixed under the offending run, and seems to be doing the trick.
Leaving aside the fact that it was allegedly replaced (with the rest of the roof) 4 years ago, initial googling suggests it has to be replaced.
I have some concerns about having to shape new flashing - not really in my skill box. However, my bigger worry is mortaring it in. Especially in the winter. And even before that, raking out the old mortar.
All of this being the case, I notice there are quite a few lead flashing alternatives ... certainly here :
What's the groupthink on such things ?