Earthing a Bathroom light switch

All I am looking to earth a bathroom light switch. Currently there is only a live & neutral in the box. The back box is metal & the existing light switch cover is plastic.

I am looking to replace the light switch cover with a metal cover, also looking to install traditional style metal light shades IP44 rated, Class 1 over 2 new sinks so will need to run a new twin core & earth from the light switch. Most of the Class 2 double insulated lights are a bit more expensive.

Two Options, for the electrical upgrade, but need your thoughts.

1) Can I run a new earth wire from my earthed shower switch to the back box of the light switch. The earth from the shower switch already goes back to the consumer unit.

2) Or alternatively, but with alot more work, run a new twin core & earth from the light switch back to the consumer unit