How to fill screw holes in gable tiles?

[Programmer]

Hiya's,

I've got some screw holes in roof tiles along a gable edge - every 2nd tile (I assume this was the done thing back in '29).

Obviously, the best way to repair/fill the holes is not to - that is, just replace the tile. That not being an available option, what is the 2nd-best way to fill and seal off the holes?

[Black Ned]

Use Silicone Sealant - comes in cartridge tubes for caulking gun and also small handy tubes

or

Black Hydroseal - bitumen tar product

both from hardware outlets