Lead on lead on Finlock concrete gutter - correct method

[caretaker]

Hi Guys
One of my neighbours had a leak running down the wall, so the roofer said it may have split in the lead, as it has flashband repair, so need to replace part of the lead.

However when they come to repair or replace.

However they did not take old lead out and remove 2 rows of slate, but he just laid lead code 4 450mm wide lead and used CT1 silicon to bond and seal it, Roofer said the old lead is stuck and would of been more damaged, so it would be easier and
Cost effective to lay new lead on top of the old lead and it will stop the leak seeping through Finlock concrete gutter.

The other side is the other neighbours gutters this is how it was, which is the old lead and applied before acropryl Fibre Glass..