Lead flashing under first floor bay windows

[ragj195]

Hi

What does the lead flashing under the first floor window do and why is there no flashing under the ground floor windows? I'm thinking about tiling the rendered curve between the up and lower windows and wondered if I could cut the flashing back a bit so there isn't so much of an overhang.

 

[datarebal]

It should go under the frame to catch any rain that get under or alongside the frame. This water is then passed to the outside.
If it was not there the structure between the windows would suffer and possibly the ceiling too.
Its good practice to have a tray under the windows.
if you tile the bay you still need the tray/flashing which is likely to be too short so will need extending rather than cutting back.